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Sample records for earth ions doped

  1. Evaluation Of Ion Exchange For Fabrication Of Rare-Earth Doped Waveguides

    NASA Astrophysics Data System (ADS)

    Howell, Brian P.; Beerling, Timothy

    1987-01-01

    Rare earth ions are frequently incorporated into lasers by doping common glasses with the ions in the glass melt. This paper describes the potential of using diffusion of the rare earth ion from molten salt baths to incorporate it in the glass. The paper discusses the molten salts, the rare earths as a group, the diffusion phenomena, the glasses, and finally the interaction of all these to produce the process. General predictions of the waveguide profile and potential problems are presented.

  2. Numerical simulations of the optical gain of crystalline fiber doped by rare earth and transition ion

    NASA Astrophysics Data System (ADS)

    Daoui, A. K.; Boubir, B.; Adouane, A.; Demagh, N.; Ghoumazi, M.

    2015-02-01

    A fiber laser is a laser whose gain medium is a doped fiber, although lasers whose cavity is made wholly of fibers have also been called fiber lasers. The gain media in a fiber laser is usually fiber doped with rare-earth ions, such as erbium (Er), neodymium (Nd), ytterbium (Yb), thulium (Tm), or praseodymium (Pr), which is doped into the core of the optical fiber, similar to those used to transmit telecommunications signals. Fiber lasers find many applications in materials processing, including cutting, welding, drilling, and marking metal. To maximize their market penetration, it is necessary to increase their output power. In this work, we present a detailed study based on the numerical simulation using MATLAB, of one of the principal characteristics of a fiber laser doped with rare earth ions and transition ion. The gain depends on several parameters such as the length of the doped fiber, the density, the pump power, noise, etc.). The used program resolves the state equations in this context together with those governing the light propagation phenomena. The developed code can also be used to study the dynamic operating modes of a doped fiber laser.

  3. Recent Advances of Rare-Earth Ion Doped Luminescent Nanomaterials in Perovskite Solar Cells.

    PubMed

    Qiao, Yu; Li, Shuhan; Liu, Wenhui; Ran, Meiqing; Lu, Haifei; Yang, Yingping

    2018-01-15

    Organic-inorganic lead halide based perovskite solar cells have received broad interest due to their merits of low fabrication cost, a low temperature solution process, and high energy conversion efficiencies. Rare-earth (RE) ion doped nanomaterials can be used in perovskite solar cells to expand the range of absorption spectra and improve the stability due to its upconversion and downconversion effect. This article reviews recent progress in using RE-ion-doped nanomaterials in mesoporous electrodes, perovskite active layers, and as an external function layer of perovskite solar cells. Finally, we discuss the challenges facing the effective use of RE-ion-doped nanomaterials in perovskite solar cells and present some prospects for future research.

  4. Recent Advances of Rare-Earth Ion Doped Luminescent Nanomaterials in Perovskite Solar Cells

    PubMed Central

    Qiao, Yu; Li, Shuhan; Liu, Wenhui; Ran, Meiqing; Lu, Haifei

    2018-01-01

    Organic-inorganic lead halide based perovskite solar cells have received broad interest due to their merits of low fabrication cost, a low temperature solution process, and high energy conversion efficiencies. Rare-earth (RE) ion doped nanomaterials can be used in perovskite solar cells to expand the range of absorption spectra and improve the stability due to its upconversion and downconversion effect. This article reviews recent progress in using RE-ion-doped nanomaterials in mesoporous electrodes, perovskite active layers, and as an external function layer of perovskite solar cells. Finally, we discuss the challenges facing the effective use of RE-ion-doped nanomaterials in perovskite solar cells and present some prospects for future research. PMID:29342950

  5. Rare earth ions doped ZnO: Synthesis, characterization and preliminary photoactivity assessment

    NASA Astrophysics Data System (ADS)

    Cerrato, Erik; Gionco, Chiara; Berruti, Ilaria; Sordello, Fabrizio; Calza, Paola; Paganini, Maria Cristina

    2018-08-01

    This work reports the effect of doping zinc oxide with lanthanide ions on structural, EPR and UV visible properties. Bare and doped samples were synthesized using the simple and green hydrothermal process. Different rare earth ions (RE = La, Ce, Pr, Er and Yb) with 1% molar ratio RE/Zn were used. The samples have been studied using X Ray Diffraction, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and UV visible diffuse reflectance spectroscopy. Finally, electron paramagnetic resonance (EPR) spectroscopy, was used to assess the materials photoactivity under UV irradiation, both in solid state, to see the charge carriers' generation and in solution, evaluating the OH• radical formation using the DMPO (5,5-Dimethyl-1-Pyrroline-N-Oxide) spin trapping technique. The results suggest that the synthesized materials could be interesting systems for the photocatalytic abatement of emerging organic persistent pollutants in wastewater treatment plants.

  6. Optical spectroscopy of rare earth ion-doped TiO2 nanophosphors.

    PubMed

    Chen, Xueyuan; Luo, Wenqin

    2010-03-01

    Trivalent rare-earth (RE3+) ion-doped TiO2 nanophosphors belong to one kind of novel optical materials and have attracted increasing attention. The luminescence properties of different RE3+ ions in various TiO2 nanomaterials have been reviewed. Much attention is paid to our recent progresses on the luminescence properties of RE3+ (RE = Eu, Er, Sm, Nd) ions in anatase TiO2 nanoparticles prepared by a sol-gel-solvothermal method. Using Eu3+ as a sensitive optical probe, three significantly different luminescence centers of Eu3+ in TiO2 nanoparticles were detected by means of site-selective spectroscopy at 10 K. Based on the crystal-field (CF) splitting of Eu3+ at each site, C2v and D2 symmetries were proposed for Eu3+ incorporated at two lattice sites. A structural model for the formation of multiple sites was proposed based on the optical behaviors of Eu3+ at different sites. Similar multi-site luminescence was observed in Sm(3+)- or Nd(3+)-doped TiO2 nanoparticles. In Eu(3+)-doped TiO2 nanoparticles, only weak energy transfer from the TiO2 host to the Eu3+ ions was observed at 10 K due to the mismatch of energy between the TiO2 band-gap and the Eu3+ excited states. On the contrary, efficient host-sensitized luminescences were realized in Sm(3+)- or Nd(3+)-doped anatase TiO2 nanoparticles due to the match of energy between TiO2 band-gap and the Sm3+ and Nd3+ excited states. The excitation spectra of both Sm(3+)- and Nd(3+)-doped samples exhibit a dominant broad peak centered at approximately 340 nm, which is associated with the band-gap of TiO2, indicating that sensitized emission is much more efficient than direct excitation of the Sm3+ and Nd3+ ions. Single lattice site emission of Er3+ in TiO2 nanocrystals can be achieved by modifying the experimental conditions. Upon excitation by a Ti: sapphire laser at 978 nm, intense green upconverted luminescence was observed. The characteristic emission of Er3+ ions was obtained both in the ultraviolet-visible (UV-vis) and

  7. Electron traps in Gd3Ga3Al2O12:Ce garnets doped with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Khanin, V. M.; Rodnyi, P. A.; Wieczorek, H.; Ronda, C. R.

    2017-05-01

    The curves of thermally stimulated luminescence of Gd3Ga3Al2O12:Ce3+ ceramics (a nominally pure sample and samples doped with rare-earth ions) are measured in the temperature range of 80-550 K. The depth and the frequency factor of electron traps established by Eu and Yb impurities are determined. An energy-level diagram of rare-earth ions in the bandgap of Gd3Ga3Al2O12 is presented.

  8. Sol-gel-derived hybrid materials multi-doped with rare-earth metal ions

    NASA Astrophysics Data System (ADS)

    Zelazowska, E.; Rysiakiewicz-Pasek, E.; Borczuch-Laczka, M.; Cholewa-Kowalska, K.

    2012-06-01

    Four different hybrid organic-inorganic materials based on TiO2-SiO2 matrices with organic additives and doped with rare-earth metal ions (III) from the group of europium, cerium, terbium, neodymium, dysprosium and samarium, were synthesized by sol-gel method. Tetraethyl orthosilicate, titanium (IV) isopropoxide and organic compounds, such as butyl acrylate, butyl methacrylate, ethyl acetoacetate, ethylene glycol dimethacrylate, ethyl acetate, propylene carbonate, organic solvents and certain inorganic salts were used in the synthesis. The inorganic part of the sols, which were used in the synthesis of all the hybrid materials, was prepared separately and then the organic parts were added. The materials obtained were aged for three weeks at room temperature and then heated in an electric oven for three hours at temperatures of 80 °C-150 °C. Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy (SEM/EDX); X-ray diffraction (XRD); Fourier transform infrared spectroscopy (KBr technique); 29Si magic-angle spinning nuclear magnetic resonance; and fluorescence spectroscopy were used for the examination of morphology, microstructure and luminescence properties, respectively. Photoluminescence properties with relatively intense narrow emission lines of Tb, Eu, Dy, Nd, Sm respectively to the RE-ions doping, were observed for all the hybrid materials.

  9. Improving soft magnetic properties of Mn-Zn ferrite by rare earth ions doping

    NASA Astrophysics Data System (ADS)

    Zhong, X. C.; Guo, X. J.; Zou, S. Y.; Yu, H. Y.; Liu, Z. W.; Zhang, Y. F.; Wang, K. X.

    2018-04-01

    Mn-Zn ferrites doped with different Sm2O3, Gd2O3, Ce2O3 or Y2O3 were prepared by traditional ceramic technology using industrial pre-sintered powders. A small amount of Sm2O3, Gd2O3, Ce2O3 or Y2O3 can significantly improve the microstructure and magnetic properties. The single spinel phase structure can be maintained with the doping amount up to 0.07 wt.%. A refined grain structure and uniform grain size distribution can be obtained by doping. For all rare earth oxides, a small amount of doping can significantly increase the permeability and reduce the coercivity and magnetic core loss. The optimized doping amount for Sm2O3 or Gd2O3 is 0.01 wt.%, while for Ce2O3 or Y2O3 is 0.03 wt.%. A further increase of the doping content will lead to reduced soft magnetic properties. The ferrite sample with 0.01 wt.% Sm2O3 exhibits the good magnetic properties with permeability, loss, and coercivity of 2586, 316 W/kg, and 24A/m, respectively, at 200 mT and 100 kHz. The present results indicate that rare earth doping can be suggested to be one of the effective ways to improve the performance of soft ferrites.

  10. Rare Earth Ion-Doped Upconversion Nanocrystals: Synthesis and Surface Modification

    PubMed Central

    Chang, Hongjin; Xie, Juan; Zhao, Baozhou; Liu, Botong; Xu, Shuilin; Ren, Na; Xie, Xiaoji; Huang, Ling; Huang, Wei

    2014-01-01

    The unique luminescent properties exhibited by rare earth ion-doped upconversion nanocrystals (UCNPs), such as long lifetime, narrow emission line, high color purity, and high resistance to photobleaching, have made them widely used in many areas, including but not limited to high-resolution displays, new-generation information technology, optical communication, bioimaging, and therapy. However, the inherent upconversion luminescent properties of UCNPs are influenced by various parameters, including the size, shape, crystal structure, and chemical composition of the UCNPs, and even the chosen synthesis process and the surfactant molecules used. This review will provide a complete summary on the synthesis methods and the surface modification strategies of UCNPs reported so far. Firstly, we summarize the synthesis methodologies developed in the past decades, such as thermal decomposition, thermal coprecipitation, hydro/solvothermal, sol-gel, combustion, and microwave synthesis. In the second part, five main streams of surface modification strategies for converting hydrophobic UCNPs into hydrophilic ones are elaborated. Finally, we consider the likely directions of the future development and challenges of the synthesis and surface modification, such as the large-scale production and actual applications, stability, and so on, of the UCNPs. PMID:28346995

  11. X-ray absorption spectroscopy and photoluminescence study of rare earth ions doped strontium sulphide phosphors

    NASA Astrophysics Data System (ADS)

    Vij, Ankush; Gautam, Sanjeev; Kumar, Vinay; Brajpuriya, R.; Kumar, Ravi; Singh, Nafa; Chae, Keun Hwa

    2013-01-01

    We present here the electronic structure and photoluminescence properties of Sm (0.1-1.0 mol%) doped SrS phosphors. The doping in SrS was probed by near-edge X-ray absorption fine structure (NEXAFS) at M5,4-edges of Sm in total electron yield mode. The simulated absorption edges using atomic multiplet calculations were correlated with experimental results, which clearly reveal the presence of trivalent state of Sm in SrS matrix. However, for Sm (1 mol%), very minor traces of Sm2+ were also observed, which have been explained by comparing the NEXAFS spectra in total electron and florescence yield mode. The PL emission of SrS:Sm comprises of three sharp bands at 567, 602 and 650 nm owing to the well-known intra 4f transitions from 4G5/2 to 6HJ (J = 5/2, 7/2, 9/2) levels of Sm3+ ions in SrS host. The effect of Ce co-doping on SrS:Sm phosphors was also investigated, which exhibits characteristic PL emission of independent ions at their respective excitation wavelengths. However, at an excitation wavelength of 393 nm, SrS:Ce,Sm exhibits the simultaneous characteristic PL emission of both ions spanning into blue-green-red region. The CIE chromaticity coordinates also clearly show the influence of excitation wavelengths on the emission colour of SrS:Ce,Sm.

  12. GeS2–In2S3–CsI Chalcogenide Glasses Doped with Rare Earth Ions for Near- and Mid-IR Luminescence

    PubMed Central

    Li, Legang; Bian, Junyi; Jiao, Qing; Liu, Zijun; Dai, Shixun; Lin, Changgui

    2016-01-01

    Chalcogenide glass has been considered as a promising host for the potential laser gain and amplifier media operating in near- and mid-IR spectral region. In this work, the IR luminescence spectra of rare earth ions (Tm3+, Er3+, and Dy3+) doped 65GeS2–25In2S3–10CsI chalcogenide glasses were measured under the excitation of an 808 nm laser diode. To the best of our knowledge, it firstly provides the luminescence spectra of a full near- and mid-IR spectral range from 1 to 4 μm in rare earth ions doped chalcogenide glasses. The results of absorption spectra, luminescence spectra, and fluorescence decay curves were obtained in these samples with singly-, co- and triply-doping behaviors of Tm3+, Er3+, and Dy3+ ions. In order to search possible efficient IR emissions, the luminescence behavior was investigated specifically with the variation of doping behaviors and dopant ions, especially in the samples co- and triply-doped active ions. The results suggest that favorable near- and mid-IR luminescence of rare earth ions can be further modified in chalcogenide glasses through an elaborated design of doping behavior and optically active ions. PMID:27869231

  13. White emission materials from glass doped with rare Earth ions: A review

    SciT

    Yasaka, P.; Kaewkhao, J., E-mail: mink110@hotmail.com; Physics Program, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, 73000

    2016-03-11

    Solid State Lighting (SSL) based devices are predicted to play a crucial role in the coming years. Development of W-LED, which have an edge over traditional lighting sources due to their compact size, higher reliability, shock resistance, interesting design possibilities, higher transparency and an extremely long lifetime. Over the fifteen trivalent lanthanide ions, Dy{sup 3+} ions doped glasses are most appropriate for white light generation because of the fact that it exhibits two intense emission bands corresponds to the {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2} (magnetic dipole) and {sup 4}F{sub 9/2}→{sup 6}H{sub 13/2} (electric dipole) transitions at around 480-500 nm and 580-600 nmmore » pertaining to blue and yellow regions respectively. In this work, the developments of Dy3+ doped in several glass structures for white emitting materials application have reviewed. Properties of Dy{sup 3+} doped in glasses were discussed for use as a solid state lighting materials application.« less

  14. The manipulated left-handedness in a rare-earth-ion-doped optical fiber by the incoherent pumping field

    NASA Astrophysics Data System (ADS)

    Zhao, Shun-Cai; Guo, Hong-Wei; Wei, Xiao-Jing

    2017-10-01

    The left-handedness was demonstrated by the simulation with a three-level quantum system in an Er3+ -dopped ZrF4-BaF2-LaF3- AlF3-NaF (ZBLAFN) optical fiber. And the left-handedness can be regulated by the incoherent pumping field. Our scheme may provide a solid candidate other than the coherent atomic vapor for left-handedness, and may extend the application of the rare-earth-ion-doped optical fiber in metamaterials and of the incoherent pumping light field in quantum optics.

  15. Physical and optical absorption studies of Fe{sup 3+} - ions doped lithium borate glasses containing certain alkaline earths

    SciT

    Bhogi, Ashok; Kumar, R. Vijaya; Kistaiah, P., E-mail: pkistaiah@yahoo.com

    Iron ion doped lithium borate glasses with the composition 15RO-25Li{sub 2}O-59B{sub 2}O{sub 3}-1Fe{sub 2}O{sub 3} (where R= Ca, Sr and Ba) have been prepared by the conventional melt quenching technique and characterized to investigate the physical and optical properties using XRD, density, molar volume and UV-Visible spectroscopy. The optical absorption spectra exhibit a band at around 460 nm which is assigned to {sup 6}A{sub 1g}(S) → 4E{sub g} (G) of Fe{sup 3+} ions with distorted octahedral symmetry. From ultraviolet absorption edges, the optical band gap and Urbach energies have been evaluated. The effect of alkaline earths on these properties ismore » discussed.« less

  16. Rare-Earth Oxide Ion (Tm3+, Ho3+, and U3+) Doped Glasses and Fibres for 1.8 to 4 Micrometer Coherent and Broadband Sources

    DTIC Science & Technology

    2006-07-24

    oxide ( TeO2 ) , fluorine- containing silicate (SiOF2) and germanate (GeOF2) glass hosts for each dopant by characterising the spectroscopic properties...Earth Oxide Ion (Tm3+, Ho3+, And U3+) Doped Glasses And Fibres For 1.8 To 4 Micrometer Coherent And Broadband Sources 5c. PROGRAM ELEMENT NUMBER 5d...Rare-earth oxide ion (Tm3+, Ho3+, and U3+) doped glasses and fibres for 1.8 to 4 micrometer coherent and broadband sources Report prepared

  17. Formation Mechanism, Structural, and Upconversion Properties of Alkaline Rare-Earth Fluoride Nanocrystals Doped With Yb3+/Er3+ Ions.

    PubMed

    Grzyb, Tomasz; Przybylska, Dominika

    2018-06-04

    Ultrasmall (9-30 nm) Yb 3+ /Er 3+ -doped, upconverting alkaline rare-earth fluorides that are promising for future applications were synthesized by the microwave-assisted hydrothermal method. The formation mechanism was proposed, indicating the influence of the stability of metal ions complexes with ethylenediaminetetraacetic acid on the composition of the product and tendency to form M 2 REF 7 (M 0.67 RE 0.33 F 2.33 ) cubic compounds in the M-RE-F systems. Their physicochemical properties (structure, morphology, and spectroscopic properties) are compared and discussed. The obtained nanoparticles exhibited emission of light in the visible spectra under excitation by 976 nm laser radiation. Excitation and emission spectra, luminescence decays, laser energy dependencies, and upconversion quantum yields were measured to determine the spectroscopic properties of prepared materials. The Yb 3+ /Er 3+ pair of ions used as dopants was responsible for an intense yellowish-green emission. The upconversion quantum yields determined for the first time for M 2 REF 7 -based materials were 0.0192 ± 0.001% and 0.0176 ± 0.001% for Sr 2 LuF 7 :Yb 3+ ,Er 3+ and Ba 2 LuF 7 :Yb 3+ ,Er 3+ respectively, the two best emitting samples. These results indicated the prepared materials are good and promising alternatives for the most studied NaYF 4 :Yb 3+ ,Er 3+ nanoparticles.

  18. Absorption and emission spectra of Ga1.7Ge25As8.3S65 glasses doped with rare-earth ions

    NASA Astrophysics Data System (ADS)

    Lupan, E. V.; Iaseniuc, O. V.; Ciornea, V. I.; Iovu, M. S.

    2016-12-01

    Excellent optical properties of chalcogenide glasses make them interesting for optoelectronic devices in the visible (VIS) and, especially, in the near- and mid-infrared (NIR and MIR) spectral regions. The rare-earth (RE3+) doped Ga17Ge25As8.3S65 glasses were prepared in evacuated ( 10-5 Pa) silica-glass ampoules which were heated up to 1000 °C at 2-4°C min-1, and then the melt was quenched. The absorption and photoluminescence spectra in the visible and near IR regions for GA1.7Ge25As8.3S65 doped with rare-earth RE+) ions (Sm3+, Nd3+, Pr3+, Dy3+ and co-doped with Ho3++Dy3+) are investigated. The energy transfer of the absorbed light in the broad band Urbach region of the host glass to the RE3+ ions is suggested for increasing the emission efficiency. The investigated Ga17Ge25As8.3S65 glasses doped with RE3+ ions are promising materials for optical amplifiers operating at 1300 and 1500 nm telecommunication windows.

  19. Photoluminescence of rare-earth ion (Eu3+, Tm3+, and Er3+)-doped and co-doped ZnNb2O6 for solar cells

    NASA Astrophysics Data System (ADS)

    Gao, Sen-Pei; Qian, Yan-Nan; Wang, Biao

    2015-08-01

    Visible converted emissions produced at an excitation of 286 nm in ZnNb2O6 ceramics doped with rare-earth ions (RE = Eu3+, Tm3+, Er3+ or a combination of these ions) were investigated with the aim of increasing the photovoltaic efficiency of solar cells. The structure of RE:ZnNb2O6 ceramics was confirmed by x-ray diffraction patterns. The undoped ZnNb2O6 could emit a blue emission under 286-nm excitation, which is attributed to the self-trapped excitons’ recombination of the efficient luminescence centers of edge-shared NbO6 groups. Upon 286-nm excitation, Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 ceramics showed blue, green, and red emissions, which correspond to the transitions of 5D0 → 7FJ (J = 1-4) (Eu3+), 1G4 → 3H6 (Tm3+), and 2H11/2/4S3/2 → 4I15/2 (Er3+), respectively. The calculated CIE chromaticity coordinates of Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 are (0.50, 0.31), (0.14, 0.19), and (0.29, 0.56), respectively. RE ion-co-doped ZnNb2O6 showed a combination of characteristic emissions. The chromaticity coordinates of Eu/Tm:ZnNb2O6, Eu/Er:ZnNb2O6, and Tm/Er:ZnNb2O6 were calculated to be (0.29, 0.24), (0.45, 0.37), and (0.17, 0.25). Project supported by the National Natural Science Foundation of China (Grant Nos. 10572155 and 10732100) and the Research Fund for the Doctoral Program of Ministry of Education, China (Grant No. 20130171130003).

  20. Effect of doping rare earths on magnetostriction characteristics of CoFe2O4 prepared from spent Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Xi, Guoxi; Zhao, Tingting; Wang, Lu; Dun, Changwei; Zhang, Ye

    2018-04-01

    Recovering spent Li-ion batteries is beneficial to the economy and environment. Therefore, this study synthesized nanoparticles of cobalt ferrite doped with different rare earth ions (Nd, Ce, and Pr) by a sol-gel auto-combustion method using spent Li-ion batteries. The effect of the different doping elements on grain sizes, structure, magnetic and magnetostrictive properties, and strain derivative were confirmed by X-ray diffraction, scanning election microscopy, vibrating sample magnetometer, and a magnetostrictive coefficient measuring system. Substitution of a small amount of Fe3+ with RE3+ in CoRExFe2-xO4 (x = 0.025, 0.05, and 0.1) had a large effect on magnetostrictive properties and strain derivative, which was improved compared with pure cobalt ferrite at low magnetic field. The maximum strain derivative (dλ/dH = -1.49 × 10-9 A-1 m at 18 kA m-1) was obtained for Nd, x = 0.05. Changes in the magnetostriction coefficients and strain derivatives were correlated with changes in cation distribution, microstructure, and magnetic anisotropy, which depended strongly on RE3+ substitution and distribution in the spinel structure.

  1. Luminescence quenching versus enhancement in WO3-NaPO3 glasses doped with trivalent rare earth ions and containing silver nanoparticles

    NASA Astrophysics Data System (ADS)

    Dousti, M. Reza; Poirier, Gael Y.; Amjad, Raja J.; de Camargo, Andrea S. S.

    2016-10-01

    We report on the influence of silver nanoparticles (NPs) on the luminescence behavior of trivalent rare earth (RE) ion doped tungsten-phosphate glasses. In order to induce the growth of NPs, the as-prepared glass samples containing silver atoms, are exposed to heat-treatment above the glass transition temperature. The surface plasmon resonance band of the Ag NPs is observed in the visible range around 420 and 537 nm in the glasses with low and high tungsten content, respectively. Such difference in spectral shift of the plasmon band is attributed to the difference in the refractive index of the two studied glass compositions. Heat-treatment results in the general increase in number of NPs, while in the case of glasses with low tungsten content, it also imposes a shift to the Ag plasmon band. The NPs size distribution (4-10 nm) was determined in good agreement with the values obtained by using Mie theory and by transmission electron microscopy. The observed quenching in the visible luminescence of glasses doped with Eu3+, Tb3+ or Er3+is attributed to energy transfer from the RE ions to Ag species, while an enhanced near-infrared emission in Er3+ doped glasses is discussed in terms of the chemical contribution of silver, rather than the most commonly claimed enhancement of localized field or energy transfer from silver species to Er3+. The results are supported by the lifetime measurements. We believe that this study gives further insight and in-depth exploration of the somewhat controversial discussions on the influence of metallic NPs plasmonic effects in RE-doped glasses.

  2. Tunable, rare earth-doped solid state lasers

    DOEpatents

    Emmett, John L.; Jacobs, Ralph R.; Krupke, William F.; Weber, Marvin J.

    1980-01-01

    Laser apparatus comprising combinations of an excimer pump laser and a rare earth-doped solid matrix, utilizing the 5d-4f radiative transition in a rare earth ion to produce visible and ultra-violet laser radiation with high overall efficiency in selected cases and relatively long radiative lifetimes.

  3. Influence of rare earth ion doping (Ce and Dy) on electrical and magnetic properties of cobalt ferrites

    NASA Astrophysics Data System (ADS)

    Hashim, Mohd.; Raghasudha, M.; Meena, Sher Singh; Shah, Jyoti; Shirsath, Sagar E.; Kumar, Shalendra; Ravinder, D.; Bhatt, Pramod; Alimuddin; Kumar, Ravi; Kotnala, R. K.

    2018-03-01

    Ce and Dy substituted Cobalt ferrites with the chemical composition CoCexDyxFe2-2xO4 (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) were synthesized through the chemical route, citrate-gel auto-combustion method. The structural characterization was carried out with the help of XRD Rieveld analysis, SEM and EDAX analysis. Formation of spinel cubic structure of the ferrites was confirmed by XRD analysis. SEM and EDAX results show that the particles are homogeneous with slight agglomeration without any impurity pickup. The effect of RE ion doping (Ce and Dy) on the dielectric, magnetic and impedance studies was systematically investigated by LCR meter, Vibrating Sample Magnetometer and Impedance analyzer respectively at room temperature in the frequency range of 10 Hz-10 MHz. Various dielectric parameters viz., dielectric constant, dielectric loss and ac conductivity were measured. The dielectric constant of all the ferrite compositions shows normal dielectric dispersion of ferrites with frequency. Impedance analysis confirms that the conduction in present ferrites is majorly due to the grain boundary mechanism. Ferrite sample with x = 0.03 show high dielectric constant, low dielectric loss and hence can be utilized in high frequency electromagnetic devices. Magnetization measurements indicate that with increase in Ce and Dy content in cobalt ferrites, the magnetization values decreased and coercivity has increased.

  4. Tunable Solid-State Quantum Memory Using Rare-Earth-Ion-Doped Crystal, Nd(3+):GaN

    DTIC Science & Technology

    2017-04-01

    by plasma-assisted molecular beam epitaxy in a modular Gen II reactor using liquid gallium, solid Nd, and a nitrogen plasma. The photoluminescence (PL...provide a tunable memory. To vary the applied field, we designed and grew a series of Nd-doped GaN p-i-n structures, strain- balanced superlattice...27 Fig. 23 Electric field vs. GaN well/ AlxGa(1-x)N barrier thickness for strain- balanced superlattice (SBSL) structures with

  5. A short review of theoretical and empirical models for characterization of optical materials doped with the transition metal and rare earth ions

    NASA Astrophysics Data System (ADS)

    Su, P.; Ma, C.-G.; Brik, M. G.; Srivastava, A. M.

    2018-05-01

    In this paper, a brief retrospective review of the main developments in crystal field theory is provided. We have examined how different crystal field models are applied to solve the problems that arise in the spectroscopy of optically active ions. Attention is focused on the joint application of crystal field and density functional theory (DFT) based models, which takes advantages of strong features of both individual approaches and allows for obtaining a complementary picture of the electronic properties of a doped crystal with impurity energy levels superimposed onto the host band structure.

  6. Rare Earth Doped High Temperature Ceramic Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study develops a spectral emittance model for films of rare earth containing materials. Although there are several possible rare earth doped high temperature materials, this study was confined to rare earth aluminum garnets. Good agreement between experimental and theoretical spectral emittances was found for erbium, thulium and erbium-holmium aluminum garnets. Spectral emittances of these films are sensitive to temperature differences across the film. Emitter efficiency is also a sensitive function of temperature. For thulium aluminum garnet the efficiency is 0.38 at 1700 K but only 0.19 at 1262 K.

  7. Supramolecular recognition control of polyethylene glycol modified N-doped graphene quantum dots: tunable selectivity for alkali and alkaline-earth metal ions.

    PubMed

    Yang, Siwei; Sun, Jing; Zhu, Chong; He, Peng; Peng, Zheng; Ding, Guqiao

    2016-02-07

    The graphene quantum dot based fluorescent probe community needs unambiguous evidence about the control on the ion selectivity. In this paper, polyethylene glycol modified N-doped graphene quantum dots (PN-GQDs) were synthesized by alkylation reaction between graphene quantum dots and organic halides. We demonstrate the tunable selectivity and sensitivity by controlling the supramolecular recognition through the length and the end group size of the polyether chain on PN-GQDs. The relationship formulae between the selectivity/detection limit and polyether chains are experimentally deduced. The polyether chain length determines the interaction between the PN-GQDs and ions with different ratios of charge to radius, which in turn leads to a good selectivity control. Meanwhile the detection limit shows an exponential growth with the size of end groups of the polyether chain. The PN-GQDs can be used as ultrasensitive and selective fluorescent probes for Li(+), Na(+), K(+), Mg(2+), Ca(2+) and Sr(2+), respectively.

  8. Scintillation of rare earth doped fluoride nanoparticles

    NASA Astrophysics Data System (ADS)

    Jacobsohn, L. G.; McPherson, C. L.; Sprinkle, K. B.; Yukihara, E. G.; DeVol, T. A.; Ballato, J.

    2011-09-01

    The scintillation response of rare earth (RE) doped core/undoped (multi-)shell fluoride nanoparticles was investigated under x-ray and alpha particle irradiation. A significant enhancement of the scintillation response was observed with increasing shells due: (i) to the passivation of surface quenching defects together with the activation of the REs on the surface of the core nanoparticle after the growth of a shell, and (ii) to the increase of the volume of the nanoparticles. These results are expected to reflect a general aspect of the scintillation process in nanoparticles, and to impact radiation sensing technologies that make use of nanoparticles.

  9. Rare Earth Doped Yttrium Aluminum Garnet (YAG) Selective Emitters

    NASA Technical Reports Server (NTRS)

    Chubb, Donald L.; Pal, AnnaMarie T.; Patton, Martin O.; Jenkins, Phillip P.

    1999-01-01

    As a result of their electron structure, rare earth ions in crystals at high temperature emit radiation in several narrow bands rather than in a continuous blackbody manner. This study presents a spectral emittance model for films and cylinders of rare earth doped yttrium aluminum garnets. Good agreement between experimental and theoretical film spectral emittances was found for erbium and holmium aluminum garnets. Spectral emittances of films are sensitive to temperature differences across the film. For operating conditions of interest, the film emitter experiences a linear temperature variation whereas the cylinder emitter has a more advantageous uniform temperature. Emitter efficiency is also a sensitive function of temperature. For holminum aluminum garnet film the efficiency is 0.35 at 1446K but only 0.27 at 1270 K.

  10. Influence of rare earth doping on thermoelectric properties of SrTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Liu, J.; Wang, C. L.; Li, Y.; Su, W. B.; Zhu, Y. H.; Li, J. C.; Mei, L. M.

    2013-12-01

    Thermoelectric properties of SrTiO3 ceramics, doped with different rare earth elements, were investigated in this work. It's found that the ionic radius of doping elements plays an important role on thermoelectric properties: SrTiO3 ceramics doped with large rare earth ions (such as La, Nd, and Sm) exhibit large power factors, and those doped with small ions (such as Gd, Dy, Er, and Y) exhibit low thermal conductivities. Therefore, a simple approach for enhancing the thermoelectric performance of SrTiO3 ceramics is proposed: mainly doped with large ions to obtain a large power factor and, simultaneously, slightly co-doped with small ions to obtain a low thermal conductivity. Based on this rule, Sr0.8La0.18Yb0.02TiO3 ceramics were prepared, whose ZT value at 1 023 K reaches 0.31, increasing by a factor of 19% compared with the single-doped counterpart Sr0.8La0.2TiO3 (ZT = 0.26).

  11. Rare-earth doped polymer waveguides and light emitting diodes

    NASA Astrophysics Data System (ADS)

    Slooff, L. H.

    2000-11-01

    Polymer-based optical waveguide amplifiers offer a low-cost alternative for inorganic waveguide amplifiers. Due to the fact that their refractive index is almost similar to that of standard optical fibers, they can be easily coupled with existing fibers at low coupling losses. Doping the polymer with rare-earth ions that can yield optical gain is not straightforward, as the rare-earth salts are poorly soluble in the polymer matrix. This thesis studies two different approaches to dope a polymer waveguide with rare-earth ions. The first one is based on organic cage-like complexes that encapsulate the rare-earth ion and are designed to provide enough coordination sites to bind the rare-earth ion and to shield it from the surrounding matrix. Chapter 2 describes the optical properties of Er-doped organic polydentate cage complexes. The complexes show clear photoluminescence at 1.54 mm with a bandwidth of 70 nm, the highest reported for an erbium-doped material so far. The luminescence lifetime is very short (~1 ms) due to coupling to vibrational overtones of O-H and C-H bonds. Due to this short luminescence lifetime, high pump powers (~1 W) are needed for optical gain in a waveguide amplifier based on these complexes. The pump power can be reduced if the Er is excited via the aromatic part of the complex, which has a higher absorption cross section. In Chapter 3 a lissamine-functionalised neodymium complex is studied in which the highly absorbing lissamine acts as a sensitiser. The lissamine is first excited into the singlet state from which intersystem crossing to the triplet state can take place. From there it can transfer its energy to the Nd ion by a Dexter transfer mechanism. Room-temperature photoluminescence at 890, 1060, and 1340 nm from Nd is observed, together with luminescence from the lissamine sensitiser at 600 nm. Photodegradation of the lissamine sensitiser is observed, which is studied in more detail in Chapter 4. The observed change in time of the

  12. Synthesis and characterization of rare-earth-doped calcium tungstate nanocrystals

    NASA Astrophysics Data System (ADS)

    Suneeta, P.; Rajesh, Ch.; Ramana, M. V.

    2018-02-01

    In this paper, we report synthesis and characterization of rare-earth-ion-doped calcium tungstate (CaWO4) nanocrystals (NCs). Rare-earth ions, such as gadolinium (Gd), neodymium (Nd), praseodymium (Pr), samarium (Sm) and holmium (Ho), were successfully doped in the CaWO4 NCs by changing the synthesis conditions. The adopted synthesis route was found to be fast and eco-friendly. Structural characterizations, such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and compositional analysis, were performed using energy dispersive analysis of X-rays (EDAX) on as-synthesized NCs. The results indicate the size of the NCs ranging between 47 to 68nm and incorporation of rare-earth ions in CaWO4 NCs.

  13. Rare-earth-ion-doped ultra-narrow-linewidth lasers on a silicon chip and applications to intra-laser-cavity optical sensing

    NASA Astrophysics Data System (ADS)

    Bernhardi, E. H.; de Ridder, R. M.; Wörhoff, K.; Pollnau, M.

    2013-03-01

    We report on diode-pumped distributed-feedback (DFB) and distributed-Bragg-reflector (DBR) channel waveguide lasers in Er-doped and Yb-doped Al2O3 on standard thermally oxidized silicon substrates. Uniform surface-relief Bragg gratings were patterned by laser-interference lithography and etched into the SiO2 top cladding. The maximum grating reflectivity exceeded 99%. Monolithic DFB and DBR cavities with Q-factors of up to 1.35×106 were realized. The Erdoped DFB laser delivered 3 mW of output power with a slope efficiency of 41% versus absorbed pump power. Singlelongitudinal- mode operation at a wavelength of 1545.2 nm was achieved with an emission line width of 1.70 0.58 kHz, corresponding to a laser Q-factor of 1.14×1011. Yb-doped DFB and DBR lasers were demonstrated at wavelengths near 1020 nm with output powers of 55 mW and a slope efficiency of 67% versus launched pump power. An Yb-doped dualwavelength laser was achieved based on the optical resonances induced by two local phase shifts in the DFB structure. A stable microwave signal at ~15 GHz with a -3-dB width of 9 kHz and a long-term frequency stability of +/- 2.5 MHz was created via the heterodyne photo-detection of the two laser wavelengths. By measuring changes in the microwave beat signal as the intra-cavity evanescent laser field interacts with micro-particles on the waveguide surface, we achieved real-time detection and accurate size measurement of single micro-particles with diameters ranging between 1 μm and 20 μm, which represents the typical size of many fungal and bacterial pathogens. A limit of detection of ~500 nm was deduced.

  14. Effects of rare earth doping on multi-core iron oxide nanoparticles properties

    NASA Astrophysics Data System (ADS)

    Petran, Anca; Radu, Teodora; Borodi, Gheorghe; Nan, Alexandrina; Suciu, Maria; Turcu, Rodica

    2018-01-01

    New multi-core iron oxide magnetic nanoparticles doped with rare earth metals (Gd, Eu) were obtained by a one step synthesis procedure using a solvothermal method for potential biomedical applications. The obtained clusters were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy-dispersive X-ray microanalysis (EDX), X-ray photoelectron spectroscopy (XPS) and magnetization measurements. They possess high colloidal stability, a saturation magnetization of up to 52 emu/g, and nearly spherical shape. The presence of rare earth ions in the obtained samples was confirmed by EDX and XPS. XRD analysis proved the homogeneous distribution of the trivalent rare earth ions in the inverse-spinel structure of magnetite and the increase of crystal strain upon doping the samples. XPS study reveals the valence state and the cation distribution on the octahedral and tetrahedral sites of the analysed samples. The observed shift of the XPS valence band spectra maximum in the direction of higher binding energies after rare earth doping, as well as theoretical valence band calculations prove the presence of Gd and Eu ions in octahedral sites. The blood protein adsorption ability of the obtained samples surface, the most important factor of the interaction between biomaterials and body fluids, was assessed by interaction with bovine serum albumin (BSA). The rare earth doped clusters surface show higher afinity for binding BSA. In vitro cytotoxicity test results for the studied samples showed no cytotoxicity in low and medium doses, establishing a potential perspective for rare earth doped MNC to facilitate multiple therapies in a single formulation for cancer theranostics.

  15. Chemical environment of rare earth ions in Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glass-ceramics doped with Dy{sup 3+}

    SciT

    Wang, Rongping, E-mail: rongping.wang@anu.edu.au; Yan, Kunlun; Luther-Davies, Barry

    2015-10-19

    We have annealed Ge{sub 28.125}Ga{sub 6.25}S{sub 65.625} glasses doped with 0.5% Dy to create glass-ceramics in order to examine the local chemical environment of the rare earth ions (REI). More than 12 times enhancement of the emission at 2.9 and 3.5 μm was achieved in glass-ceramics produced using prolonged annealing time. Elemental mapping showed clear evidence that Ga{sub 2}S{sub 3} crystalline grains with a size of 50 nm were dispersed in a Ge-S glass matrix in the glass-ceramics, and the REI could only be found near the Ga{sub 2}S{sub 3} crystalline grains. From the unchanged lineshape of the emissions at 2.9 andmore » 3.5 μm and lack of splitting of the absorption peaks, we concluded that the REI were bonded to Ga on the surface of the Ga{sub 2}S{sub 3} crystals.« less

  16. Sensing Using Rare-Earth-Doped Upconversion Nanoparticles

    PubMed Central

    Hao, Shuwei; Chen, Guanying; Yang, Chunhui

    2013-01-01

    Optical sensing plays an important role in theranostics due to its capability to detect hint biochemical entities or molecular targets as well as to precisely monitor specific fundamental psychological processes. Rare-earth (RE) doped upconversion nanoparticles (UCNPs) are promising for these endeavors due to their unique frequency converting capability; they emit efficient and sharp visible or ultraviolet (UV) luminescence via use of ladder-like energy levels of RE ions when excited at near infrared (NIR) light that are silent to tissues. These features allow not only a high penetration depth in biological tissues but also a high detection sensitivity. Indeed, the energy transfer between UCNPs and biomolecular or chemical indicators provide opportunities for high-sensitive bio- and chemical-sensing. A temperature-sensitive change of the intensity ratio between two close UC bands promises them for use in temperature mapping of a single living cell. In this work, we review recent investigations on using UCNPs for the detection of biomolecules (avidin, ATP, etc.), ions (cyanide, mecury, etc.), small gas molecules (oxygen, carbon dioxide, ammonia, etc.), as well as for in vitro temperature sensing. We also briefly summarize chemical methods in synthesizing UCNPs of high efficiency that are important for the detection limit. PMID:23650480

  17. ACTIVE MEDIA: BaY2F8 single crystals doped with rare-earth ions as promising up-conversion media for UV and VUV lasers

    NASA Astrophysics Data System (ADS)

    Pushkar', A. A.; Uvarova, T. V.; Molchanov, V. N.

    2008-04-01

    BaY2F8 crystals are studied as promising active media for UV and VUV lasers. The up-conversion pumping of rare-earth activators is proposed to solve problems related to the solarisation of the medium and the selection of pump sources. The technology of growing oriented BaY2F8 single crystals is developed and the influence of the crystal orientation on the growth rate and quality of single crystals is determined.

  18. Review on dielectric properties of rare earth doped barium titanate

    SciT

    Ismail, Fatin Adila, E-mail: fatinadilaismail@gmail.com; Osman, Rozana Aina Maulat, E-mail: rozana@unimap.edu.my; Frontier Materials Research, Seriab, 01000 Kangar, Perlis

    2016-07-19

    Rare earth doped Barium Titanate (BaTiO{sub 3}) were studied due to high permittivity, excellent electrical properties and have wide usage in various applications. This paper reviewed on the electrical properties of RE doped BaTiO{sub 3} (RE: Lanthanum (La), Erbium (Er), Samarium (Sm), Neodymium (Nd), Cerium (Ce)), processing method, phase transition occurred and solid solution range for complete study. Most of the RE doped BaTiO{sub 3} downshifted the Curie temperature (T{sub C}). Transition temperature also known as Curie temperature, T{sub C} where the ceramics had a transition from ferroelectric to a paraelectric phase. In this review, the dielectric constant of La-dopedmore » BaTiO{sub 3}, Er-doped BaTiO{sub 3}, Sm-doped BaTiO{sub 3}, Nd-doped BaTiO{sub 3} and Ce-doped BaTiO{sub 3} had been proved to increase and the transition temperature or also known as T{sub C} also lowered down to room temperature as for all the RE doped BaTiO{sub 3} except for Er-doped BaTiO{sub 3}.« less

  19. Porous silicon - rare earth doped xerogel and glass composites

    NASA Astrophysics Data System (ADS)

    Balakrishnan, S.; Gun'ko, Yurii K.; Perova, T. S.; Rafferty, A.; Astrova, E. V.; Moore, R. A.

    2005-06-01

    The development of components for photonics applications is growing exponentially. The sol-gel method is now recognised as a convenient and flexible way to deposit oxide or glass films on a variety of hosts, including porous silicon. In the present work we incorporated erbium and europium doped xerogel into porous silicon and developed new porous silicon - rare earth doped glass composites. Various characteris-ation techniques including FTIR, Raman Spectroscopy, Thermal Gravimetric Analysis and Scanning Electron Microscopy were employed in this work.

  20. Production yield of rare-earth ions implanted into an optical crystal

    SciT

    Kornher, Thomas, E-mail: t.kornher@physik.uni-stuttgart.de; Xia, Kangwei; Kolesov, Roman

    2016-02-01

    Rare-earth (RE) ions doped into desired locations of optical crystals might enable a range of novel integrated photonic devices for quantum applications. With this aim, we have investigated the production yield of cerium and praseodymium by means of ion implantation. As a measure, the collected fluorescence intensity from both implanted samples and single centers was used. With a tailored annealing procedure for cerium, a yield up to 53% was estimated. Praseodymium yield amounts up to 91%. Such high implantation yield indicates a feasibility of creation of nanopatterned rare-earth doping and suggests strong potential of RE species for on-chip photonic devices.

  1. Novel online security system based on rare-earth-doped glass microbeads

    NASA Astrophysics Data System (ADS)

    Officer, Simon; Prabhu, G. R.; Pollard, Pat; Hunter, Catherine; Ross, Gary A.

    2004-06-01

    A novel fluorescent security label has been produced that could replace numerous conventional fluorescent dyes in document security. This label utilizes rare earth ions doped in a borosilicate glass matrix to produce sharp spectral fluorescence peaks with characteristic long lifetimes due to the rare earth ions. These are subsequently detected by an online detection system based on fluorescence and the long lifetimes to avoid any interference from other fluorophores present in the background. Security is further enhanced by the interaction of the rare earth ions with each other and the effect of the host on the emission spectra and therefore the number of permutations that could be produced. This creates a very secure label with various applications for the security market.

  2. Mixedness determination of rare earth-doped ceramics

    NASA Astrophysics Data System (ADS)

    Czerepinski, Jennifer H.

    The lack of chemical uniformity in a powder mixture, such as clustering of a minor component, can lead to deterioration of materials properties. A method to determine powder mixture quality is to correlate the chemical homogeneity of a multi-component mixture with its particle size distribution and mixing method. This is applicable to rare earth-doped ceramics, which require at least 1-2 nm dopant ion spacing to optimize optical properties. Mixedness simulations were conducted for random heterogeneous mixtures of Nd-doped LaF3 mixtures using the Concentric Shell Model of Mixedness (CSMM). Results indicate that when the host to dopant particle size ratio is 100, multi-scale concentration variance is optimized. In order to verify results from the model, experimental methods that probe a mixture at the micro, meso, and macro scales are needed. To directly compare CSMM results experimentally, an image processing method was developed to calculate variance profiles from electron images. An in-lens (IL) secondary electron image is subtracted from the corresponding Everhart-Thornley (ET) secondary electron image in a Field-Emission Scanning Electron Microscope (FESEM) to produce two phases and pores that can be quantified with 50 nm spatial resolution. A macro was developed to quickly analyze multi-scale compositional variance from these images. Results for a 50:50 mixture of NdF3 and LaF3 agree with the computational model. The method has proven to be applicable only for mixtures with major components and specific particle morphologies, but the macro is useful for any type of imaging that produces excellent phase contrast, such as confocal microscopy. Fluorescence spectroscopy was used as an indirect method to confirm computational results for Nd-doped LaF3 mixtures. Fluorescence lifetime can be used as a quantitative method to indirectly measure chemical homogeneity when the limits of electron microscopy have been reached. Fluorescence lifetime represents the

  3. Effect of silver ions and clusters on the luminescence properties of Eu-doped borate glasses

    SciT

    Jiao, Qing, E-mail: jiaoqing@nbu.edu.cn; Wang, Xi; Qiu, Jianbei

    2015-12-15

    Highlights: • Ag{sup +} and Ag clusters are investigated in the borate glasses via ion exchange method. • The aggregation of silver ions to the clusters was controlled by the ion exchange concentration. • Eu{sup 3+}/Eu{sup 2+} ions emission was enhanced with the sensitization of the silver species. • Energy transfer process from Ag ions and Ag clusters to Eu ions is identified by the lifetime measurements. - Abstract: Silver ions and clusters were applied to Eu{sup 3+}-doped borate glasses via the Ag{sup +}–Na{sup +} ion exchange method. Eu{sup 3+}/Eu{sup 2+} ion luminescence enhancement was achieved after silver ion exchange.more » Absorption spectra showed no band at 420 nm, which indicates that silver nanoparticles can be excluded as a silver state in the glass. Silver ion aggregation into clusters during the ion exchange process may be inferred. The effect of silver ions and clusters on rare earth emissions was investigated using spectral information and lifetime measurements. Significant luminescence enhancements were observed from the energy transfer of Ag{sup +} ions and clusters to Eu{sup 3+}/Eu{sup 2+} ions, companied with the silver ions aggregated into the clusters state. The results of this research may extend the current understanding of interactions between rare-earth ions and Ag species.« less

  4. 40 CFR 721.10423 - Complex strontium aluminate, rare earth doped (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... earth doped (generic). 721.10423 Section 721.10423 Protection of Environment ENVIRONMENTAL PROTECTION... New Uses for Specific Chemical Substances § 721.10423 Complex strontium aluminate, rare earth doped... substances identified generically as complex strontium aluminate, rare earth doped (PMNs P-12-22, P-12-23, P...

  5. Environment spectrum and coherence behaviours in a rare-earth doped crystal for quantum memory.

    PubMed

    Gong, Bo; Tu, Tao; Zhou, Zhong-Quan; Zhu, Xing-Yu; Li, Chuan-Feng; Guo, Guang-Can

    2017-12-21

    We theoretically investigate the dynamics of environment and coherence behaviours of the central ion in a quantum memory based on a rare-earth doped crystal. The interactions between the central ion and the bath spins suppress the flip-flop rate of the neighbour bath spins and yield a specific environment spectral density S(ω). Under dynamical decoupling pulses, this spectrum provides a general scaling for the coherence envelope and coherence time, which significantly extend over a range on an hour-long time scale. The characterized environment spectrum with ultra-long coherence time can be used to implement various quantum communication and information processing protocols.

  6. Alkaline earth metal doped tin oxide as a novel oxygen storage material

    SciT

    Dong, Qiang, E-mail: dong@tagen.tohoku.ac.jp; Yin, Shu; Yoshida, Mizuki

    2015-09-15

    Alkaline earth metal doped tin oxide (SnO{sub 2}) hollow nanospheres with a diameter of 50 nm have been synthesized successfully via a facial solvothermal route in a very simple system composed of only ethanol, acetic acid, SnCl{sub 4}·5H{sub 2}O and A(NO{sub 3}){sub 2}·xH{sub 2}O (A = Mg, Ca, Sr, Ba). The synthesized undoped SnO{sub 2} and A-doped SnO{sub 2} hollow nanospheres were characterized by the oxygen storage capacity (OSC), X-ray diffraction, transmission electron microscopy and the Brunauer–Emmet–Teller (BET) technique. The OSC values of all samples were measured using thermogravimetric-differential thermal analysis. The incorporation of alkaline earth metal ion into tinmore » oxide greatly enhanced the thermal stability and OSC. Especially, Ba-doped SnO{sub 2} hollow nanospheres calcined at 1000 °C for 20 h with a BET surface area of 61 m{sup 2} g{sup −1} exhibited the considerably high OSC of 457 μmol-O g{sup −1} and good thermal stability. Alkaline earth metal doped tin oxide has the potential to be a novel oxygen storage material.« less

  7. Research of green emitting rare-earth doped materials as potential quantum-cutter

    NASA Astrophysics Data System (ADS)

    Moine, Bernard; Beauzamy, Lena; Gredin, Patrick; Wallez, Gilles; Labeguerie, Jessica

    2008-03-01

    Because the energy of vacuum ultraviolet (VUV) photons emitted by xenon plasma discharge is more than twice that of visible photons, quantum cutting appears to be a promising process in rare-earth doped materials in order to obtain efficient phosphors for mercury free lighting devices as well as for plasma display panels. With an aim of application, it is important to take into account the emitting color of the developed new phosphors. Most of the time, this leads to use systems with at least two kinds of rare earth ions: one of them playing the role of energy sensitizer, and the other one being in charge of emitting the light of the suitable color. We focus our attention on green rare-earth doped materials. In order to get very efficient phosphors, it is not only necessary to get the highest possible quantum yield, but also to have a material characterized by a strong absorption in the VUV range. Borate and fluoride matrices doped with Dy 3+/Tb 3+ couples of ions are selected according to the position of the 5d band of dysprosium as green emitters.

  8. Site preference for luminescent activator ions in doped fluoroperovskite RbZnF3.

    PubMed

    Saroj, Sanjay Kumar; Nagarajan, Rajamani

    2018-08-05

    With the dual objective of investigating the site preferences of larger sized activator ions and to append luminescence property to the perovskite structured RbZnF 3 , doping of manganese(II), cerium(III), europium(III) and terbium(III) ions (5 mol%) was carried out. Although cubic symmetry of RbZnF 3 was preserved for all the doped samples, site preference of rare-earth ions for the A-site Rb + leading to an inverse perovskite arrangement has been noticed from careful analysis of lattice parameters from refinement of powder X-ray diffraction data. Undoped RbZnF 3 exhibited rod-like morphology in the transmission electron microscopic image. In addition to an intense band around 230 nm assignable to the charge transfer from ZnF 3 - to Rb + , typical transitions of respective dopant ions were observed in their UV-visible spectra. The doped samples showed luminescence in blue, green and red regions and time decay experiments suggested uniform dispersion of them without any clustering effect. The lower phonon energy of RbZnF 3 matrix by virtue of the presence of heavier rubidium at the A-site together with its doping with rare-earth ions resulting in an inverse perovskite like arrangement could favour their utility in various practical applications. Copyright © 2018 Elsevier B.V. All rights reserved.

  9. Recent advances in rare earth doped alkali-alkaline earth borates for solid state lighting applications

    NASA Astrophysics Data System (ADS)

    Verma, Shefali; Verma, Kartikey; Kumar, Deepak; Chaudhary, Babulal; Som, Sudipta; Sharma, Vishal; Kumar, Vijay; Swart, Hendrik C.

    2018-04-01

    As a novel class of inorganic phosphor, the alkali-alkaline earth borate phosphors have gained huge attention due to their charming applications in solid-state lighting (SSL) and display devices. The current research drive shows that phosphors based on the alkali-alkaline earth borates have transformed the science and technology due to their high transparency over a broad spectral range, their flexibility in structure and durability for mechanical and high-laser applications. Recent advances in various aspects of rare-earth (RE) doped borate based phosphors and their utilizations in SSL and light emitting diodes are summarized in this review article. Moreover, the present status and upcoming scenario of RE-doped borate phosphors were reviewed in general along with the proper credential from the existing literature. It is believed that this review is a sole compilation of crucial information about the RE-doped borate phosphors in a single platform.

  10. Structure and Magnetic Properties of Rare Earth Doped Transparent Alumina

    NASA Astrophysics Data System (ADS)

    Limmer, Krista; Neupane, Mahesh; Chantawansri, Tanya

    Recent experimental studies of rare earth (RE) doped alumina suggest that the RE induced novel phase-dependent structural and magnetic properties. Motivated by these efforts, the effects of RE doping of alpha and theta alumina on the local structure, magnetic properties, and phase stability have been examined in this first principles study. Although a direct correlation between the magnetic field dependent materials properties observed experimentally and calculated from first principles is not feasible because of the applied field and the scale, the internal magnetic properties and other properties of the doped materials are evaluated. The RE dopants are shown to increase the substitutional site volume as well as increasingly distort the site structure as a function of ionic radii. Doping both the alpha (stable) and theta (metastable) phases enhanced the relative stability of the theta phase. The energetic doping cost and internal magnetic moment were shown to be a function of the electronic configuration of the RE-dopant, with magnetic moment directly proportional to the number of unpaired electrons and doping cost being inversely related.

  11. Effective doping of low energy ions into superfluid helium droplets

    SciT

    Zhang, Jie; Chen, Lei; Freund, William M.

    2015-08-21

    We report a facile method of doping cations from an electrospray ionization (ESI) source into superfluid helium droplets. By decelerating and stopping the ion pulse of reserpine and substance P from an ESI source in the path of the droplet beam, about 10{sup 4} ion-doped droplets (one ion per droplet) can be recorded, corresponding to a pickup efficiency of nearly 1 out of 1000 ions. We attribute the success of this simple approach to the long residence time of the cations in the droplet beam. The resulting size of the doped droplets, on the order of 10{sup 5}/droplet, is measuredmore » using deflection and retardation methods. Our method does not require an ion trap in the doping region, which significantly simplifies the experimental setup and procedure for future spectroscopic and diffraction studies.« less

  12. Optical properties of rare earth doped transparent oxyfluoride glass ceramics

    NASA Astrophysics Data System (ADS)

    Mendez-Ramos, J.; Lavin, V.; Martin, I. R.; Rodriguez-Mendoza, U. R.; Rodriguez, V. D.; Lozano-Gorrin, A. D.; Nunez, P.

    2003-01-01

    Optical properties of Eu3+ ions in oxyfluoride glasses and glass ceramics doped with low concentration (0.1 mol%) have been analysed and compared with previous results for high concentrated samples (2.5 mol%). The Eu3+ ions in the low dopant concentration glass ceramics are diluted into like crystalline environments with higher symmetry and lower coupled phonons energy than in the precursor glasses. Fluorescence line narrowing measurements indicate the presence of two main fluoride site distributions for the Eu3+ ions in these low concentrated glass ceramics.

  13. Rare earth doped zinc oxide varistors

    DOEpatents

    McMillan, April D.; Modine, Frank A.; Lauf, Robert J.; Alim, Mohammad A.; Mahan, Gerald D.; Bartkowiak, Miroslaw

    1998-01-01

    A varistor includes a Bi-free, essentially homogeneous sintered body of a ceramic composition including, expressed as nominal weight %, 0.2-4.0% oxide of at least one rare earth element, 0.5-4.0% Co.sub.3 O.sub.4, 0.05-0.4% K.sub.2 O, 0.05-0.2% Cr.sub.2 O.sub.3, 0-0.2% CaO, 0.00005-0.01% Al.sub.2 O.sub.3, 0-2% MnO, 0-0.05% MgO, 0-0.5% TiO.sub.3, 0-0.2% SnO.sub.2, 0-0.02% B.sub.2 O.sub.3, balance ZnO.

  14. Rare earth doped zinc oxide varistors

    DOEpatents

    McMillan, A.D.; Modine, F.A.; Lauf, R.J.; Alim, M.A.; Mahan, G.D.; Bartkowiak, M.

    1998-12-29

    A varistor includes a Bi-free, essentially homogeneous sintered body of a ceramic composition including, expressed as nominal weight %, 0.2--4.0% oxide of at least one rare earth element, 0.5--4.0% Co{sub 3}O{sub 4}, 0.05--0.4% K{sub 2}O, 0.05--0.2% Cr{sub 2}O{sub 3}, 0--0.2% CaO, 0.00005--0.01% Al{sub 2}O{sub 3}, 0--2% MnO, 0--0.05% MgO, 0--0.5% TiO{sub 3}, 0--0.2% SnO{sub 2}, 0--0.02% B{sub 2}O{sub 3}, balance ZnO. 4 figs.

  15. Upconversion-pumped luminescence efficiency of rare-earth-doped hosts sensitized with trivalent ytterbium

    SciT

    Page, R.H.; Schaffers, K.I.; Waide, P.A.

    We discuss the upconversion luminescence efficiencies of phosphors that generate red, green, and blue light. The phosphors studied are single crystals and powders co-doped with Er{sup 3+} and Yb{sup 3+}, and with Tm{sup 3+} and Yb{sup 3+}. The Yb ions are pumped near 980 nm; transfers of two or three quanta to the co-doped rare earth ion generate visible luminescence. The main contribution embodied in this work is the quantitative measurement of this upconversion efficiency, based on the use of a calibrated integrating sphere, determination of the fraction of pump light absorbed, and careful control of the pump laser beammore » profile. The green phosphors are the most efficient, yielding efficiency values as high as 4 %, with the red and blue materials giving 1 - 2 %. Saturation was observed in all cases, suggesting that populations of upconversion steps of the ions are maximized at higher power. Quasi-CW modeling of the intensity- dependent upconversion efficiency was attempted; input data included level lifetimes, transition cross sections, and cross-relaxation rate coefficients. The saturation of the Yb,Er:fluoride media is explained as the pumping of Er{sup 3+} ions into a bottleneck (long-lived state)- the {sup 4}I{sub 13/2} metastable level, making them unavailable for further excitation transfer. 32 refs., 5 figs., 3 tabs.« less

  16. Antibacterial, Antifungal and Nematicidal Activities of Rare Earth Ions.

    PubMed

    Wakabayashi, Tokumitsu; Ymamoto, Ayumi; Kazaana, Akira; Nakano, Yuta; Nojiri, Yui; Kashiwazaki, Moeko

    2016-12-01

    Despite the name, rare earth elements are relatively abundant in soil. Therefore, these elements might interact with biosphere during the history of life. In this study, we have examined the effect of rare earth ions on the growth of bacteria, fungi and soil nematode. All rare earth ions, except radioactive promethium that we have not tested, showed antibacterial and antifungal activities comparable to that of copper ions, which is widely used as antibacterial metals in our daily life. Rare earth ions also have nematicidal activities as they strongly perturb the embryonic development of the nematode, Caenorhabditis elegans. Interestingly, the nematicidal activity increased with increasing atomic number of lanthanide ions. Since the rare earth ions did not show high toxicity to the human lymphoblastoid cell line or even stimulate the growth of the cultured cells at 1 mM, it raised the possibility that we can substitute rare earth elements for the antibacterial metals usually used because of their safety.

  17. Upconversion improvement in KLaF4:Yb3+/Er3+ nanoparticles by doping Al3+ ions

    NASA Astrophysics Data System (ADS)

    Zhou, Haifang; Wang, Xiechun; Lai, Yunfeng; Cheng, Shuying; Zheng, Qiao; Yu, Jinlin

    2017-10-01

    Rare-earth ion-doped upconversion (UC) materials show great potential applications in optical and optoelectronic devices due to their novel optical properties. In this work, hexagonal KLaF4:Yb3+/Er3+ nanoparticles (NPs) were successfully synthesized by a hydrothermal method, and remarkably enhanced upconversion luminescence in green and red emission bands in KLaF4:Yb3+/Er3+ NPs has been achieved by doping Al3+ ions under 980 nm excitation. Compared to the aluminum-free KLaF4:Yb3+/Er3+ NPs sample, the UC fluorescence intensities of the green and red emissions of NPs doped with 10 at.% Al3+ ions were significantly enhanced by 5.9 and 7.3 times, respectively. Longer lifetimes of the doped samples were observed for the 4S3/2 state and 4F9/2 state. The underlying reason for the UC enhancement by doping Al3+ ions was mainly ascribed to distortion of the local symmetry around Er3+ ions and adsorption reduction of organic ligands on the surface of NPs. In addition, the influence of doping Al3+ ions on the structure and morphology of the NPs samples was also discussed.

  18. Ion Implantation Doping of Inertial Confinement Fusion Targets

    DOE PAGES

    Shin, S. J.; Lee, J. R. I.; van Buuren, T.; ...

    2017-12-19

    Controlled doping of inertial confinement fusion (ICF) targets is needed to enable nuclear diagnostics of implosions. Here in this study, we demonstrate that ion implantation with a custom-designed carousel holder can be used for azimuthally uniform doping of ICF fuel capsules made from a glow discharge polymer (GDP). Particular emphasis is given to the selection of the initial wall thickness of GDP capsules as well as implantation and postimplantation annealing parameters in order to minimize capsule deformation during a postimplantation thermal treatment step. In contrast to GDP, ion-implanted high-density carbon exhibits excellent thermal stability and ~100% implantation efficiency for themore » entire range of ion doses studied (2 × 10 14 to 1 × 10 16 cm -2) and for annealing temperatures up to 700°C. Lastly, we demonstrate a successful doping of planar Al targets with isotopes of Kr and Xe to doses of ~10 17 cm -2.« less

  19. Electrochemical Doping of Halide Perovskites with Ion Intercalation.

    PubMed

    Jiang, Qinglong; Chen, Mingming; Li, Junqiang; Wang, Mingchao; Zeng, Xiaoqiao; Besara, Tiglet; Lu, Jun; Xin, Yan; Shan, Xin; Pan, Bicai; Wang, Changchun; Lin, Shangchao; Siegrist, Theo; Xiao, Qiangfeng; Yu, Zhibin

    2017-01-24

    Halide perovskites have recently been investigated for various solution-processed optoelectronic devices. The majority of studies have focused on using intrinsic halide perovskites, and the intentional incoporation of dopants has not been well explored. In this work, we discovered that small alkali ions, including lithium and sodium ions, could be electrochemically intercalated into a variety of halide and pseudohalide perovskites. The ion intercalation caused a lattice expansion of the perovskite crystals and resulted in an n-type doping of the perovskites. Such electrochemical doping improved the conductivity and changed the color of the perovskites, leading to an electrochromism with more than 40% reduction of transmittance in the 450-850 nm wavelength range. The doped perovskites exhibited improved electron injection efficiency into the pristine perovskite crystals, resulting in bright light-emitting diodes with a low turn-on voltage.

  20. Ion Implantation Doping of Inertial Confinement Fusion Targets

    SciT

    Shin, S. J.; Lee, J. R. I.; van Buuren, T.

    Controlled doping of inertial confinement fusion (ICF) targets is needed to enable nuclear diagnostics of implosions. Here in this study, we demonstrate that ion implantation with a custom-designed carousel holder can be used for azimuthally uniform doping of ICF fuel capsules made from a glow discharge polymer (GDP). Particular emphasis is given to the selection of the initial wall thickness of GDP capsules as well as implantation and postimplantation annealing parameters in order to minimize capsule deformation during a postimplantation thermal treatment step. In contrast to GDP, ion-implanted high-density carbon exhibits excellent thermal stability and ~100% implantation efficiency for themore » entire range of ion doses studied (2 × 10 14 to 1 × 10 16 cm -2) and for annealing temperatures up to 700°C. Lastly, we demonstrate a successful doping of planar Al targets with isotopes of Kr and Xe to doses of ~10 17 cm -2.« less

  1. Multicomponent, Rare-Earth-Doped Thermal-Barrier Coatings

    NASA Technical Reports Server (NTRS)

    Miller, Robert A.; Zhu, Dongming

    2005-01-01

    Multicomponent, rare-earth-doped, perovskite-type thermal-barrier coating materials have been developed in an effort to obtain lower thermal conductivity, greater phase stability, and greater high-temperature capability, relative to those of the prior thermal-barrier coating material of choice, which is yttria-partially stabilized zirconia. As used here, "thermal-barrier coatings" (TBCs) denotes thin ceramic layers used to insulate air-cooled metallic components of heat engines (e.g., gas turbines) from hot gases. These layers are generally fabricated by plasma spraying or physical vapor deposition of the TBC materials onto the metal components. A TBC as deposited has some porosity, which is desirable in that it reduces the thermal conductivity below the intrinsic thermal conductivity of the fully dense form of the material. Undesirably, the thermal conductivity gradually increases because the porosity gradually decreases as a consequence of sintering during high-temperature service. Because of these and other considerations such as phase transformations, the maximum allowable service temperature for yttria-partially stabilized zirconia TBCs lies in the range of about 1,200 to 1,300 C. In contrast, the present multicomponent, rare-earth-doped, perovskite-type TBCs can withstand higher temperatures.

  2. Thermoluminescent properties of rare earth doped lithium strontium borate phosphors

    NASA Astrophysics Data System (ADS)

    Jakathamani, S.; Annalakshmi, O.; Jose, M. T.

    2018-04-01

    Thermoluminescence (TL) of borates is remarkable in the field of radiation dosimetry because they can detect both neutron and gamma radiations. Usually, the TL efficiency of pure borates is low and hence dopants have to be added to increase their TL output. Their sensitivity and thermal stability vary widely and depend strongly on the preparation method. In this study polycrystalline powders of different rare earth doped thermoluminescent phosphors of Lithium Strontium borate (LSB) were synthesized by solid state sintering technique. Among the different rare earth dopants, the phosphor doped with cerium was found to have a simple glow curve structure with a dosimetric peak at around 265°C for a heating rate of 5°C/s. In order to study the effect of dopant on the TL characteristics, LSB phosphor with different concentrations of Ce dopant was synthesized and the TL intensity was found to be maximum for a dopant concentration of 0.7 mol%. All other important dosimetric characteristics like dose response and fading were carried out for the LSB:Ce (0.7 mol%) phosphor. Kinetic parameters like trap depth and frequency factor were determined using Peak shape method from Chen's equation.

  3. Radiation hardening of rare-earth doped fiber amplifiers

    NASA Astrophysics Data System (ADS)

    Vivona, Marilena; Girard, Sylvain; Marcandella, Claude; Pinsard, Emmanuel; Laurent, Arnaud; Robin, Thierry; Cadier, Benoît; Cannas, Marco; Boukenter, Aziz; Ouerdane, Y.

    2017-11-01

    We investigated the radiation hardening of optical fiber amplifiers operating in space environments. Through a real-time analysis in active configuration, we evaluated the role of Ce in the improvement of the amplifier performance against ionizing radiations. Ce-codoping is an efficient hardening solution, acting both in the limitation of defects in the host glass matrix of RE-doped optical fibers and in the stabilization of lasing properties of the Er3+-ions. On the one hand, in the near-infrared region, radiation induced attenuation measurements show the absence of radiation induced P-related defect species in host glass matrix of the Ce-codoped active fibers; on the other hand, in the Ce-free fiber, the higher lifetime variation shows stronger local modifications around the Er3+-ions with the absence of Ce.

  4. Measurements of defect structures by positron annihilation lifetime spectroscopy of the tellurite glass TeO2-P2O5-ZnO-LiNbO3 doped with ions of rare earth elements: Er3+, Nd3+ and Gd3+

    NASA Astrophysics Data System (ADS)

    Golis, E.; Yousef, El. S.; Reben, M.; Kotynia, K.; Filipecki, J.

    2015-12-01

    The objective of the study was the structural analysis of the TeO2-P2O5-ZnO-LiNbO3 tellurite glasses doped with ions of the rare-earth elements: Er3+, Nd3+ and Gd3+ based on the PALS (Positron Annihilation Lifetime Spectroscopy) method of measuring positron lifetimes. Values of positron lifetimes and the corresponding intensities may be connected with the sizes and number of structural defects, such as vacancies, mono-vacancies, dislocations or pores, the sizes of which range from a few angstroms to a few dozen nanometres. Experimental positron lifetime spectrum revealed existence of two positron lifetime components τ1 and τ2. Their interpretation was based on two-state positron trapping model where the physical parameters are the annihilation velocity and positron trapping rate.

  5. Europium-doped mesoporous titania thin films: rare-earth locations and emission fluctuations under illumination.

    PubMed

    Leroy, Celine Marie; Cardinal, Thierry; Jubera, Veronique; Treguer-Delapierre, Mona; Majimel, Jerome; Manaud, Jean Pierre; Backov, Renal; Boissière, Cedric; Grosso, David; Sanchez, Clement; Viana, Bruno; Pellé, Fabienne

    2008-10-06

    Herein, Eu(III)-doped 3D mesoscopically ordered arrays of mesoporous and nanocrystalline titania are prepared and studied. The rare-earth-doped titania thin films-synthesized via evaporation-induced self-assembly (EISA)-are characterized by using environmental ellipsoporosimetry, electronic microscopy (i.e. high-resolution scanning electron microscopy, HR-SEM, and transmission electron microscopy, HR-TEM), X-ray diffraction, and luminescence spectroscopy. Structural characterizations show that high europium-ion loadings can be incorporated into the titanium-dioxide walls without destroying the mesoporous arrangement. The luminescence properties of Eu(III) are investigated by using steady-state and time-resolved spectroscopy via excitation of the Eu(III) ions through the titania host. Using Eu(III) luminescence as a probe, the europium-ion sites can be addressed with at least two different environments within the mesoporous framework, namely, a nanocrystalline environment and a glasslike one. Emission fluctuations ((5)D(0)-->(7)F(2)) are observed upon continuous UV excitation in the host matrix. These fluctuations are attributed to charge trapping and appear to be strongly dependent on the amount of europium and the level of crystallinity.

  6. Study of nitrogen ion doping of titanium dioxide films

    NASA Astrophysics Data System (ADS)

    Ramos, Raul; Scoca, Diego; Borges Merlo, Rafael; Chagas Marques, Francisco; Alvarez, Fernando; Zagonel, Luiz Fernando

    2018-06-01

    This study reports on the properties of nitrogen doped titanium dioxide (TiO2) thin films considering the application as a transparent conducting oxide (TCO). Sets of thin films were prepared by sputtering a titanium target under oxygen atmosphere on a quartz substrate at 400 or 500 °C. Films were then doped at the same temperature by 150 eV nitrogen ions. The films were prepared in Anatase phase which was maintained after doping. Up to 30 at% nitrogen concentration was obtained at the surface, as determined by in situ X-ray photoelectron spectroscopy (XPS). Such high nitrogen concentration at the surface lead to nitrogen diffusion into the bulk which reached about 25 nm. Hall measurements indicate that average carrier density reached over 1019 cm-3 with mobility in the range of 0.1-1 cm2 V-1 s-1. Resistivity about 3 · 10-1 Ω cm could be obtained with 85% light transmission at 550 nm. These results indicate that low energy implantation is an effective technique for TiO2 doping that allows an accurate control of the doping process independently from the TiO2 preparation. Moreover, this doping route seems promising to attain high doping levels without significantly affecting the film structure. Such approach could be relevant for preparation of N:TiO2 transparent conducting electrodes (TCE).

  7. Influence of other rare earth ions on the optical refrigeration efficiency in Yb:YLF crystals.

    PubMed

    Di Lieto, Alberto; Sottile, Alberto; Volpi, Azzurra; Zhang, Zhonghan; Seletskiy, Denis V; Tonelli, Mauro

    2014-11-17

    We investigated the effect of rare earth impurities on the cooling efficiency of Yb³⁺:LiYF₄ (Yb:YLF). The refrigeration performance of two single crystals, doped with 5%-at. Yb and with identical history but with different amount of contaminations, have been compared by measuring the cooling efficiency curves. Spectroscopic and elemental analyses of the samples have been carried out to identify the contaminants, to quantify their concentrations and to understand their effect on the cooling efficiencies. A model of energy transfer processes between Yb and other rare earth ions is suggested, identifying Erbium and Holmium as elements that produce a detrimental effect on the cooling performance.

  8. Optimization of rare-earth-doped fluorides for infrared lasers

    NASA Astrophysics Data System (ADS)

    Peterson, Rita Dedomenico

    2000-11-01

    The rare-earth-doped fluoride crystals Tm,Dy:BaY2F8 (Tm,Dy:BYF), Yb,Pr:NaYF4 (Yb,Pr:NYF), and Nd:NYF show considerable promise as infrared laser materials, operating at 3 μm, 1.3 μm, and 1.06 μm respectively. Lasing has been reported previously on all three ionic transitions, but not in these crystals. Optimization of these materials for laser applications requires a more complete spectroscopic characterization than is currently available, particularly with regard to the key parameters of fluorescence lifetime and stimulated emission cross section. To further the optimization process, polarized absorption and emission have been measured for Tm,Dy:BYF, Yb,Pr:NYF, and Nd:NYF, and relevant fluorescence lifetimes have been measured or estimated. For Tm,Dy:BYF and Yb,Pr:NYF which rely upon sensitization, energy transfer parameters were calculated. Results were used in a mathematical model to determine the conditions in which lasing may be obtained. The long upper laser level lifetime in Tm,Dy:BYF translates into low threshold pump intensity, but the ability to reach threshold depends strongly on active ion concentration. The short lifetime in Yb,Pr:NYF leads to much higher threshold pump intensities, but lasing is still attainable if resonator loss is minimized. In Nd:NYF lasing was demonstrated, with a maximum of 60 mW output from an absorbed pump power of 345 mW, and a slope efficiency of 21%. Thresholds were high owing to resonator losses near 9%. Two chief issues involving the optimization of these laser materials were identified and explored. First, identification of the orientation for which emission cross section is highest is complicated in Tm,Dy:BYF by the presence of strong magnetic dipole radiation on the 3 μm transition. This effect makes it necessary to account for the polarization of both the electric and magnetic fields of the emitted radiation when determining an optimal crystal orientation, an accounting further complicated by the low symmetry of

  9. Fiber-optic thermometer application of thermal radiation from rare-earth end-doped SiO{sub 2} fiber

    SciT

    Katsumata, Toru, E-mail: katsumat@toyo.jp; Morita, Kentaro; Komuro, Shuji

    2014-08-15

    Visible light thermal radiation from SiO{sub 2} glass doped with Y, La, Ce, Pr, Nd, Eu, Tb, Dy, Ho, Er, Tm, Yb, and Lu were studied for the fiber-optic thermometer application based on the temperature dependence of thermal radiation. Thermal radiations according to Planck's law of radiation are observed from the SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu at the temperature above 1100 K. Thermal radiations due to f-f transitions of rare-earth ions are observed from the SiO{sub 2} fibers doped with Nd, Dy, Ho, Er, Tm, and Yb at the temperature above 900more » K. Peak intensities of thermal radiations from rare-earth doped SiO{sub 2} fibers increase sensitively with temperature. Thermal activation energies of thermal radiations by f-f transitions seen in Nd, Dy, Ho, Er, Tm, and Yb doped SiO{sub 2} fibers are smaller than those from SiO{sub 2} fibers doped with Y, La, Ce, Pr, Eu, Tb, and Lu. Thermal radiation due to highly efficient f-f transitions in Nd, Dy, Ho, Er, Tm, and Yb ions emits more easily than usual thermal radiation process. Thermal radiations from rare-earth doped SiO{sub 2} are potentially applicable for the fiber-optic thermometry above 900 K.« less

  10. Electronic Characteristics of Rare Earth Doped GaN Schottky Diodes

    DTIC Science & Technology

    2013-03-21

    REPORT TYPE Master’s Thesis 3. DATES COVERED (From – To) 04 Sep 2011 - Mar 2013 4. TITLE AND SUBTITLE ELECTRONIC CHARACTERISTICS OF RARE EARTH ...ELECTRONIC CHARACTERISTICS OF RARE EARTH DOPED GaN SCHOTTKY DIODES THESIS Aaron B. Blanning...United States. AFIT-ENP-13-M-03 Electronic Characteristics of Rare Earth Doped GaN Schottky Diodes THESIS Presented to the Faculty

  11. Physical and electrochemical properties of alkaline earth doped, rare earth vanadates

    NASA Astrophysics Data System (ADS)

    Adijanto, Lawrence; Balaji Padmanabhan, Venu; Holmes, Kevin J.; Gorte, Raymond J.; Vohs, John M.

    2012-06-01

    The effect of partial substitution of alkaline earth (AE) ions, Sr2+ and Ca2+, for the rare earth (RE) ions, La3+, Ce3+, Pr3+, and Sm3+, on the physical properties of REVO4 compounds were investigated. The use of the Pechini method to synthesize the vanadates allowed for high levels of AE substitution to be obtained. Coulometric titration was used to measure redox isotherms for these materials and showed that the addition of the AE ions increased both reducibility and electronic conductivity under typical solid oxide fuel cell (SOFC) anode conditions, through the formation of compounds with mixed vanadium valence. In spite of their high electronic conductivity, REVO4-yttira stabilized zirconia (YSZ) composite anodes exhibited only modest performance when used in SOFCs operating with H2 fuel at 973 K due to their low catalytic activity. High performance was obtained, however, after the addition of a small amount of catalytically active Pd to the anode.

  12. Magnetic properties of rare-earth-doped La0.7Sr0.3MnO3.

    PubMed

    Veverka, Pavel; Kaman, Ondřej; Knížek, Karel; Novák, Pavel; Maryško, Miroslav; Jirák, Zdeněk

    2017-01-25

    Rare-earth-doped ferromagnetic manganites La 0.63 RE 0.07 Sr 0.30 MnO 3 (RE  =  Gd, Tb, Dy, and Ho) are synthesized in the form of sintered ceramics and nanocrystalline phases with the mean size of crystallites  ≈30 nm. The electronic states of the dopants are investigated by SQUID magnetometry and theoretically interpreted based on the calculations of the crystal field splitting of rare-earth energy levels. The samples show the orthorhombic perovskite structure of Ibmm symmetry, with a complete FM order of Mn spins in bulk and reduced order in nanoparticles. Non-zero moments are also detected at the perovskite A sites, which can be attributed to magnetic polarization of the rare-earth dopants. The measurements in external field up to 70 kOe show a standard Curie-type contribution of the spin-only moments of Gd 3+ ions, whereas Kramers ions Dy 3+ and non-Kramers ions Ho 3+ contribute by Ising moments due to their doublet ground states. The behaviour of non-Kramers ions Tb 3+ is anomalous, pointing to singlet ground state with giant Van Vleck paramagnetism. The Tb 3+ doping leads also to a notably increased coercivity compared to other La 0.63 RE 0.07 Sr 0.30 MnO 3 systems.

  13. Synthesis of rare earth doped TiO2 nanorods as photocatalysts for lignin degradation.

    PubMed

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; Moon, Ji-Won; Gu, Baohua; Wang, Wei

    2015-10-28

    A two-step process is developed to synthesize rare earth doped titania nanorods (RE-TiO2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE-TiO2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO2 NRs or the commercial P25 TiO2 photocatalyst. Using methyl orange (MO) as a probing molecule, we demonstrate that Eu-TiO2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10(-3) s(-1). The La(3+), Sm(3+), Eu(3+) and Er(3+) doped TiO2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO2. We further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.

  14. Synthesis of rare earth doped TiO 2 nanorods as photocatalysts for lignin degradation

    DOE PAGES

    Song, Liang; Zhao, Xueyuan; Cao, Lixin; ...

    2015-09-10

    In this paper, a two-step process is developed to synthesize rare earth doped titania nanorods (RE–TiO 2 NRs) as photocatalysts for efficient degradation of lignin under simulated sunlight irradiation. In this approach, protonated titanate nanotubes with layered structures were first prepared by a hydrothermal approach, and rare earth metal ions were subsequently bound to the negatively charged surface of the synthesized titanate via electrostatic incorporation. The as-synthesized RE–TiO 2 NRs after calcination generally showed much higher photocatalytic efficiencies than those of undoped TiO 2 NRs or the commercial P25 TiO 2 photocatalyst. Using methyl orange (MO) as a probing molecule,more » we demonstrate that Eu–TiO 2 NRs are among the best for degrading MO, with an observed rate constant of 4.2 × 10 -3 s -1. The La 3+, Sm 3+, Eu 3+ and Er 3+ doped TiO 2 NRs also showed higher photocatalytic efficiencies in degrading MO than the commercial P25 TiO 2. Finally, we further demonstrate that lignin can be photodegraded effectively and rapidly at room temperature under simulated sunlight through two reaction routes, which could be important in controlling ways of lignin depolymerization or the formation of reaction products.« less

  15. Method of fabricating optical waveguides by ion implantation doping

    DOEpatents

    Appleton, Bill R.; Ashley, Paul R.; Buchal, Christopher J.

    1989-01-01

    A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO.sub.3 crystals are implanted with high concentrations of Ti dopant at ion energies of about 350 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000.degree. C. produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality single crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguides properties.

  16. Method of fabricating optical waveguides by ion implantation doping

    DOEpatents

    Appleton, B.R.; Ashley, P.R.; Buchal, C.J.

    1987-03-24

    A method for fabricating high-quality optical waveguides in optical quality oxide crystals by ion implantation doping and controlled epitaxial recrystallization is provided. Masked LiNbO/sub 3/ crystals are implanted with high concentrations of Ti dopant at ion energies of about 360 keV while maintaining the crystal near liquid nitrogen temperature. Ion implantation doping produces an amorphous, Ti-rich nonequilibrium phase in the implanted region. Subsequent thermal annealing in a water-saturated oxygen atmosphere at up to 1000/degree/C produces solid-phase epitaxial regrowth onto the crystalline substrate. A high-quality crystalline layer results which incorporates the Ti into the crystal structure at much higher concentrations than is possible by standard diffusion techniques, and this implanted region has excellent optical waveguiding properties.

  17. Computer modelling of BaY2F8: defect structure, rare earth doping and optical behaviour

    NASA Astrophysics Data System (ADS)

    Amaral, J. B.; Couto Dos Santos, M. A.; Valerio, M. E. G.; Jackson, R. A.

    2005-10-01

    BaY2F8, when doped with rare earth elements, is a material of interest in the development of solid-state laser systems, especially for use in the infrared region. This paper presents the application of a computational technique, which combines atomistic modelling and crystal field calculations, in a study of rare earth doping of the material. Atomistic modelling is used to calculate the intrinsic defect structure and the symmetry and detailed geometry of the dopant ion-host lattice system, and this information is then used to calculate the crystal field parameters, which are an important indicator in assessing the optical behaviour of the dopant-crystal system. Energy levels are then calculated for the Dy3+-substituted material, and comparisons with the results of recent experimental work are made.

  18. Magnetomigration of rare-earth ions in inhomogeneous magnetic fields.

    PubMed

    Franczak, Agnieszka; Binnemans, Koen; Jan Fransaer

    2016-10-05

    The effects of external inhomogenous (gradient) magnetic fields on the movement of the rare-earth ions: Dy 3+ , Gd 3+ and Y 3+ , in initially homogeneous aqueous solutions have been investigated. Differences in the migration of rare-earth ions in gradient magnetic fields were observed, depending on the magnetic character of the ions: paramagnetic ions of Dy 3+ and Gd 3+ move towards regions of the sample where the magnetic field gradient is the strongest, while diamagnetic ions of Y 3+ move in the opposite direction. It has been showed that the low magnetic field gradients, such the ones generated by permanent magnets, are sufficient to observe the magnetomigration effects of the ions in solution. The present work clearly establishes the behavior of magnetically different ions in initially homogeneous aqueous solutions exposed to magnetic field gradients. To this avail, a methodology for measuring the local concentration differences of metal ions in liquid samples was developed.

  19. High Resolution Fluorescence Imaging of Cancers Using Lanthanide Ion-Doped Upconverting Nanocrystals

    PubMed Central

    Naccache, Rafik; Rodríguez, Emma Martín; Bogdan, Nicoleta; Sanz-Rodríguez, Francisco; de la Cruz, Maria del Carmen Iglesias; de la Fuente, Ángeles Juarranz; Vetrone, Fiorenzo; Jaque, Daniel; Solé, José García; Capobianco, John A.

    2012-01-01

    During the last decade inorganic luminescent nanoparticles that emit visible light under near infrared (NIR) excitation (in the biological window) have played a relevant role for high resolution imaging of cancer. Indeed, semiconductor quantum dots (QDs) and metal nanoparticles, mostly gold nanorods (GNRs), are already commercially available for this purpose. In this work we review the role which is being played by a relatively new class of nanoparticles, based on lanthanide ion doped nanocrystals, to target and image cancer cells using upconversion fluorescence microscopy. These nanoparticles are insulating nanocrystals that are usually doped with small percentages of two different rare earth (lanthanide) ions: The excited donor ions (usually Yb3+ ion) that absorb the NIR excitation and the acceptor ions (usually Er3+, Ho3+ or Tm3+), that are responsible for the emitted visible (or also near infrared) radiation. The higher conversion efficiency of these nanoparticles in respect to those based on QDs and GNRs, as well as the almost independent excitation/emission properties from the particle size, make them particularly promising for fluorescence imaging. The different approaches of these novel nanoparticles devoted to “in vitro” and “in vivo” cancer imaging, selective targeting and treatment are examined in this review. PMID:24213500

  20. Growth of rare-earth doped single crystal yttrium aluminum garnet fibers

    NASA Astrophysics Data System (ADS)

    Bera, Subhabrata; Nie, Craig D.; Harrington, James A.; Cheng, Long; Rand, Stephen C.; Li, Yuan; Johnson, Eric G.

    2018-02-01

    Rare-earth doped single crystal (SC) yttrium aluminum garnet (YAG) fibers have great potential as high-power laser gain media. SC fibers combine the superior material properties of crystals with the advantages of a fiber geometry. Improving processing techniques, growth of low-loss YAG SC fibers have been reported. A low-cost technique that allows for the growth of optical quality Ho:YAG single crystal (SC) fibers with different dopant concentrations have been developed and discussed. This technique is a low-cost sol-gel based method which offers greater flexibility in terms of dopant concentration. Self-segregation of Nd ions in YAG SC fibers have been observed. Such a phenomenon can be utilized to fabricate monolithic SC fibers with graded index.

  1. Monitoring the orientation of rare-earth-doped nanorods for flow shear tomography.

    PubMed

    Kim, Jongwook; Michelin, Sébastien; Hilbers, Michiel; Martinelli, Lucio; Chaudan, Elodie; Amselem, Gabriel; Fradet, Etienne; Boilot, Jean-Pierre; Brouwer, Albert M; Baroud, Charles N; Peretti, Jacques; Gacoin, Thierry

    2017-09-01

    Rare-earth phosphors exhibit unique luminescence polarization features originating from the anisotropic symmetry of the emitter ion's chemical environment. However, to take advantage of this peculiar property, it is necessary to control and measure the ensemble orientation of the host particles with a high degree of precision. Here, we show a methodology to obtain the photoluminescence polarization of Eu-doped LaPO 4 nanorods assembled in an electrically modulated liquid-crystalline phase. We measure Eu 3+ emission spectra for the three main optical configurations (σ, π and α, depending on the direction of observation and the polarization axes) and use them as a reference for the nanorod orientation analysis. Based on the fact that flowing nanorods tend to orient along the shear strain profile, we use this orientation analysis to measure the local shear rate in a flowing liquid. The potential of this approach is then demonstrated through tomographic imaging of the shear rate distribution in a microfluidic system.

  2. Fluorine-doping in titanium dioxide by ion implantation technique

    NASA Astrophysics Data System (ADS)

    Yamaki, T.; Umebayashi, T.; Sumita, T.; Yamamoto, S.; Maekawa, M.; Kawasuso, A.; Itoh, H.

    2003-05-01

    We implanted 200 keV F + in single crystalline titanium dioxide (TiO 2) rutile at a nominal fluence of 1 × 10 16 to 1 × 10 17 ions cm -2 and then thermally annealed the implanted sample in air. The radiation damage and its recovery process during the annealing were analyzed by Rutherford backscattering spectrometry in channeling geometry and variable-energy positron annihilation spectroscopy. The lattice disorder was completely recovered at 1200 °C by the migration of point defects to the surface. According to secondary ion mass spectrometry analysis, the F depth profile was shifted to a shallower region along with the damage recovery and this resulted in the formation of an F-doped layer where the impurity concentration steadily increased toward the surface. The F doping proved to provide a modification to the conduction-band edge of TiO 2, as assessed by theoretical band calculations.

  3. Luminescence properties of Tm3+ ions single-doped YF3 materials in an unconventional excitation region.

    PubMed

    Chen, Yuan; Liu, Qing; Lin, Han; Yan, Xiaohong

    2018-05-01

    According to the spectral distribution of solar radiation at the earth's surface, under the excitation region of 1150 to 1350 nm, the up-conversion luminescence of Tm 3+ ions was investigated. The emission bands were matched well with the spectral response region of silicon solar cells, achieved by Tm 3+ ions single-doped yttrium fluoride (YF 3 ) phosphor, which was different from the conventional Tm 3+ /Yb 3+ ion couple co-doped materials. Additionally, the similar emission bands of Tm 3+ ions were achieved under excitation in the ultraviolet region. It is expected that via up-conversion and down-conversion routes, Tm 3+ -sensitized materials could convert photons to the desired wavelengths in order to reduce the energy loss of silicon solar cells, thereby enhancing the photovoltaic efficiency. Copyright © 2018 John Wiley & Sons, Ltd.

  4. Study of optical properties of cerium ion doped barium aluminate phosphor

    SciT

    Lohe, P. P., E-mail: prachiti.lohe2012@gmail.com; Omanwar, S. K.; Bajaj, N. S.

    2016-05-06

    In the recent years due to their various optical and technological applications aluminate materials have attracted attention of several researchers. When these materials are doped with rare earth ions they show properties favorable for many optical applications such as high quantum efficiencies. These materials are used in various applications such as lamp phosphors, optically and thermoluminescence dosimeter etc Barium aluminate BaAl{sub 2}O{sub 4} doped with Ce is well known long lasting phosphor. This paper reports synthesis of BaAl{sub 2}O{sub 4}: Ce phosphor prepared by a simple combustion synthesis. The samples were characterized for the phase purity, chemical bonds and luminescentmore » properties.« less

  5. Thermoelectric Properties of Barium Plumbate Doped by Alkaline Earth Oxides

    NASA Astrophysics Data System (ADS)

    Eufrasio, Andreza; Bhatta, Rudra; Pegg, Ian; Dutta, Biprodas

    Ceramic oxides are now being considered as a new class of thermoelectric materials because of their high stability at elevated temperatures. Such materials are especially suitable for use as prospective thermoelectric power generators because high temperatures are encountered in such operations. The present investigation uses barium plumbate (BaPbO3) as the starting material, the thermoelectric properties of which have been altered by judicious cation substitutions. BaPbO3 is known to exhibit metallic properties which may turn semiconducting as a result of compositional changes without precipitating a separate phase and/or altering the basic perovskite crystal structure. Perovskite structures are noted for their large interstitial spaces which can accommodate a large variety of ``impurity'' ions. As BaPbO3 has high electrical conductivity, σ = 2.43x105Ω-1 m-1 at room temperature, its thermopower, S, is relatively low, 23 μV/K, as expected. With a thermal conductivity, k, of 4.83Wm-1K-1, the figure of merit (ZT =S2 σ Tk-1) of BaPbO3 is only 0.01 at T = 300K. The objective of this investigation is to study the variation of thermoelectric properties of BaPbO3 as Ba and Pb ions are systematically substituted by alkaline earth ions.

  6. Enhanced near-infrared photoacoustic imaging of silica-coated rare-earth doped nanoparticles.

    PubMed

    Sheng, Yang; Liao, Lun-De; Bandla, Aishwarya; Liu, Yu-Hang; Yuan, Jun; Thakor, Nitish; Tan, Mei Chee

    2017-01-01

    Near-infrared photoacoustic (PA) imaging is an emerging diagnostic technology that utilizes the tissue transparent window to achieve improved contrast and spatial resolution for deep tissue imaging. In this study, we investigated the enhancement effect of the SiO 2 shell on the PA property of our core/shell rare-earth nanoparticles (REs) consisting of an active rare-earth doped core of NaYF 4 :Yb,Er (REDNPs) and an undoped NaYF 4 shell. We observed that the PA signal amplitude increased with SiO 2 shell thickness. Although the SiO 2 shell caused an observed decrease in the integrated fluorescence intensity due to the dilution effect, fluorescence quenching of the rare earth emitting ions within the REDNPs cores was successfully prevented by the undoped NaYF 4 shell. Therefore, our multilayer structure consisting of an active core with successive functional layers was demonstrated to be an effective design for dual-modal fluorescence and PA imaging probes with improved PA property. The result from this work addresses a critical need for the development of dual-modal contrast agent that advances deep tissue imaging with high resolution and signal-to-noise ratio. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Nanophotonic photon echo memory based on rare-earth-doped crystals

    NASA Astrophysics Data System (ADS)

    Zhong, Tian; Kindem, Jonathan; Miyazono, Evan; Faraon, Andrei; Caltech nano quantum optics Team

    2015-03-01

    Rare earth ions (REIs) are promising candidates for implementing solid-state quantum memories and quantum repeater devices. Their high spectral stability and long coherence times make REIs a good choice for integration in an on-chip quantum nano-photonic platform. We report the coupling of the 883 nm transition of Neodymium (Nd) to a Yttrium orthosilicate (YSO) photonic crystal nano-beam resonator, achieving Purcell enhanced spontaneous emission by 21 times and increased optical absorption. Photon echoes were observed in nano-beams of different doping concentrations, yielding optical coherence times T2 up to 80 μs that are comparable to unprocessed bulk samples. This indicates the remarkable coherence properties of Nd are preserved during nanofabrication, therefore opening the possibility of efficient on-chip optical quantum memories. The nano-resonator with mode volume of 1 . 6(λ / n) 3 was fabricated using focused ion beam, and a quality factor of 3200 was measured. Purcell enhanced absorption of 80% by an ensemble of ~ 1 × 106 ions in the resonator was measured, which fulfills the cavity impedance matching condition that is necessary to achieve quantum storage of photons with unity efficiency.

  8. Use of thulium-sensitized rare earth-doped low phonon energy crystalline hosts for IR sources

    PubMed Central

    2013-01-01

    Crystalline hosts with low phonon energies enable novel energy transfer processes when doped with rare earth ions. Two applications of energy transfer for rare earth ions in thulium-sensitized low phonon energy crystals that result in infrared luminescence are discussed. One application is an endothermic, phonon-assisted cross-relaxation process in thulium-doped yttrium chloride that converts lattice phonons to infrared emission, which raises the possibility of a fundamentally new method for achieving solid-state optical cooling. The other application is an optically pumped mid-IR phosphor using thulium-praseodymium-doped potassium lead chloride that converts 805-nm diode light to broadband emission from 4,000 to 5,500 nm. These two applications in chloride crystals are discussed in terms of critical radii calculated from Forster-Dexter energy transfer theory. It is found that the critical radii for electric dipole-dipole interactions in low phonon energy chloride crystals are comparable to those in conventional oxide and fluoride crystals. It is the reduction in multi-phonon relaxation rates in chloride crystals that enable these additional energy transfer processes and infrared luminescence. PMID:24180684

  9. Use of thulium-sensitized rare earth-doped low phonon energy crystalline hosts for IR sources.

    PubMed

    Ganem, Joseph; Bowman, Steven R

    2013-11-01

    Crystalline hosts with low phonon energies enable novel energy transfer processes when doped with rare earth ions. Two applications of energy transfer for rare earth ions in thulium-sensitized low phonon energy crystals that result in infrared luminescence are discussed. One application is an endothermic, phonon-assisted cross-relaxation process in thulium-doped yttrium chloride that converts lattice phonons to infrared emission, which raises the possibility of a fundamentally new method for achieving solid-state optical cooling. The other application is an optically pumped mid-IR phosphor using thulium-praseodymium-doped potassium lead chloride that converts 805-nm diode light to broadband emission from 4,000 to 5,500 nm. These two applications in chloride crystals are discussed in terms of critical radii calculated from Forster-Dexter energy transfer theory. It is found that the critical radii for electric dipole-dipole interactions in low phonon energy chloride crystals are comparable to those in conventional oxide and fluoride crystals. It is the reduction in multi-phonon relaxation rates in chloride crystals that enable these additional energy transfer processes and infrared luminescence.

  10. Use of thulium-sensitized rare earth-doped low phonon energy crystalline hosts for IR sources

    NASA Astrophysics Data System (ADS)

    Ganem, Joseph; Bowman, Steven R.

    2013-11-01

    Crystalline hosts with low phonon energies enable novel energy transfer processes when doped with rare earth ions. Two applications of energy transfer for rare earth ions in thulium-sensitized low phonon energy crystals that result in infrared luminescence are discussed. One application is an endothermic, phonon-assisted cross-relaxation process in thulium-doped yttrium chloride that converts lattice phonons to infrared emission, which raises the possibility of a fundamentally new method for achieving solid-state optical cooling. The other application is an optically pumped mid-IR phosphor using thulium-praseodymium-doped potassium lead chloride that converts 805-nm diode light to broadband emission from 4,000 to 5,500 nm. These two applications in chloride crystals are discussed in terms of critical radii calculated from Forster-Dexter energy transfer theory. It is found that the critical radii for electric dipole-dipole interactions in low phonon energy chloride crystals are comparable to those in conventional oxide and fluoride crystals. It is the reduction in multi-phonon relaxation rates in chloride crystals that enable these additional energy transfer processes and infrared luminescence.

  11. Multilayer Thermal Barrier Coating (TBC) Architectures Utilizing Rare Earth Doped YSZ and Rare Earth Pyrochlores

    NASA Technical Reports Server (NTRS)

    Schmitt, Michael P.; Rai, Amarendra K.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    To allow for increased gas turbine efficiencies, new insulating thermal barrier coatings (TBCs) must be developed to protect the underlying metallic components from higher operating temperatures. This work focused on using rare earth doped (Yb and Gd) yttria stabilized zirconia (t' Low-k) and Gd2Zr2O7 pyrochlores (GZO) combined with novel nanolayered and thick layered microstructures to enable operation beyond the 1200 C stability limit of current 7 wt% yttria stabilized zirconia (7YSZ) coatings. It was observed that the layered system can reduce the thermal conductivity by approximately 45 percent with respect to YSZ after 20 hr of testing at 1316 C. The erosion rate of GZO is shown to be an order to magnitude higher than YSZ and t' Low-k, but this can be reduced by almost 57 percent when utilizing a nanolayered structure. Lastly, the thermal instability of the layered system is investigated and thought is given to optimization of layer thickness.

  12. Scintillation properties of rare-earth doped NaPO3-Al(PO3)3 glasses

    NASA Astrophysics Data System (ADS)

    Kuro, Tomoaki; Okada, Go; Kawaguchi, Noriaki; Fujimoto, Yutaka; Masai, Hirokazu; Yanagida, Takayuki

    2016-12-01

    We systematically investigated photoluminescence (PL), scintillation and dosimeter properties of rare-earth (RE) doped NaPO3-Al(PO3)3 (NAP) glasses. The NAP glasses doped with a series of RE ions (La-Yb, except Pm) with a consistent concentration (0.3 wt%) were prepared by the conventional melt-quenching method. The PL and scintillation decay time profiles showed fast (ns) and slow (μs or ms) components: the fast components from 15 to 100 ns were due to the host or 5d-4f transition emission, and the slow components from 15 μs to 5 ms were due to the 4f-4f transitions of RE. The thermally stimulated luminescence (TSL) was evaluated as a dosimeter property, and glow peaks appeared around 400 °C in all the samples. The TSL dose response function was examined in the dose range from 10 mGy to 10 Gy. Among the samples tested, Nd and Tb doped glasses showed higher signal by at least one order of magnitude than those of non-doped and other RE-doped samples. Over the dose range tested, the TSL signals are linearly related with the incident X-ray dose, showing a potential for practical applications.

  13. Effects of rare earth ionic doping on microstructures and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} ceramics

    SciT

    Xue, Renzhong; Department of Technology and Physics, Zhengzhou University of Light Industry, Zhengzhou 450002; Chen, Zhenping, E-mail: xrzbotao@163.com

    2015-06-15

    Graphical abstract: The dielectric constant decreases monotonically with reduced RE doping ion radius and is more frequency independent compared with that of pure CCTO sample. - Highlights: • The mean grain sizes decrease monotonically with reduced RE doping ionic radius. • Doping gives rise to the monotonic decrease of ϵ{sub r} with reduced RE ionic radius. • The nonlinear coefficient and breakdown field increase with RE ionic doping. • α of all the samples is associated with the potential barrier width rather than Φ{sub b}. - Abstract: Ca{sub 1–x}R{sub x}Cu{sub 3}Ti{sub 4}O{sub 12}(R = La, Nd, Eu, Gd, Er; xmore » = 0 and 0.005) ceramics were prepared by the conventional solid-state method. The influences of rare earth (RE) ion doping on the microstructure, dielectric and electrical properties of CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO) ceramics were investigated systematically. Single-phase formation is confirmed by XRD analyses. The mean grain size decreases monotonically with reduced RE ion radius. The EDS results reveal that RE ionic doping reduces Cu-rich phase segregation at the grain boundaries (GBs). Doping gives rise to the monotonic decrease of dielectric constant with reduced RE ionic radius but significantly improves stability with frequency. The lower dielectric loss of doped samples is obtained due to the increase of GB resistance. In addition, the nonlinear coefficient and breakdown field increase with RE ionic doping. Both the fine grains and the enhancement of potential barrier at GBs are responsible for the improvement of the nonlinear current–voltage properties in doped CCTO samples.« less

  14. Rare Earth Doped IR Fiber Lasers For Medical Applications

    NASA Astrophysics Data System (ADS)

    Esterowitz, Leon; Allen, Roger

    1989-06-01

    Trivalent rare earth doped lasers in fluorozirconate glasses and fibers that lase between 2 and 3 μm are reviewed. There have been a large number of laser-fiber optic systems below 2pm developed for clinical microsurgery at a variety of sites. The required flexibility of the fiber optic waveguide varies with the clinical use, such as: intraocular (through a small diameter rigid tube), endoscopically accessible pulmonary and gastric mucosa (through a port of a fiber-optic endoscope of intermediate flexibility), and intra-arterial (as an integral part of a flexible catheter, which in the case of the coronaries must be very flexible so as to negotiate abrupt bends and bifurcations without damage to the vessels). Laser energy absorbed by tissue is capable of coagulation of tissue (denaturation of structural proteins), melting of fatty deposits or other structures (solid or gel to liquid phase transitions), as well as direct breakage of chemical bonds by high energy photons. It is of general interest to develop a pulsed laser system transmitted through flexible fiber optics that is capable of precise ablation of targeted tissue with minimal damage to the remaining tissue. Ideally, the device should be able to ablate any tissue because of the general absorptive properties of tissue, and not a specific chromophore such as melanin or hemoglobin, the concentration of which varies widely among tissues. Two obvious ubiquitous chromophores have been widely discussed: 1) proteins and nucleic acids whose high concentration and absorption coefficients lead to strong tissue absorption in the ultraviolet and 2) water whose strong infrared absorption bands have been widely utilized in CO2 laser surgery. Non-linear absorption occurring at very high power densities (~1 GW/cm2) has been shown to be very effective for non-invasive ocular (an optically transparent field) microsurgery at the image plane of a slit lamp, but this approach appears impractical in fiber optic systems because

  15. Recent developments in the growth, processing, and testing of rare earth doped YVO{sub 4} single crystals

    SciT

    Mizell, G.; Fay, W.R.; Alekel, T. III

    1994-12-31

    The production of the laser host material YVO{sub 4} via high temperature solution growth (HTSG) is described as a facile alternative for producing optical quality crystals for research. The effects of dopant concentration on optical absorption properties in 0.7% and 3% Nd:YVO{sub 4} crystals are discussed. The rare earths ions Ho{sup 3+} and Er{sup 3+} have been doped into YVO{sub 4} with the HTSG method, and inaugural optical properties of Ho{sub 0.04}Y{sub 0.96}VO{sub 4} are presented.

  16. Influence of rare earth ions on microstructural and optical properties of ZnO nanostructures

    SciT

    Riyajuddin, Sk., E-mail: riyaj5303@gmail.com; Ahmad, Shabbir; Faizan, M.

    2016-05-23

    Pure and 3% rare earth ions (Nd{sup 3+} & Gd{sup 3+}) doped ZnO samples were synthesized by sol-gel method, followed by annealing at temperature 450°C for 2hr. The samples were characterized by XRD, FTIR and UV-visible spectroscopy. XRD result confirmed single phase nature of all samples with crystalline structure. The average crystallite size of the doped samples found to be decreases as caculated using Debye-Scherrer’s formula. FTIR spectra indicate absorption band centered at 464 cm{sup −1} which is attributed to Zn-O lattice vibration. It confirms the formaton of compounds. UV-visible spectroscopy was used to study the optical properties and band gapmore » of the synthesised materials using Tauc’s relation.« less

  17. Ions doped melanin nanoparticle as a multiple imaging agent.

    PubMed

    Ha, Shin-Woo; Cho, Hee-Sang; Yoon, Young Il; Jang, Moon-Sun; Hong, Kwan Soo; Hui, Emmanuel; Lee, Jung Hee; Yoon, Tae-Jong

    2017-10-10

    Multimodal nanomaterials are useful for providing enhanced diagnostic information simultaneously for a variety of in vivo imaging methods. According to our research findings, these multimodal nanomaterials offer promising applications for cancer therapy. Melanin nanoparticles can be used as a platform imaging material and they can be simply produced by complexation with various imaging active ions. They are capable of specifically targeting epidermal growth factor receptor (EGFR)-expressing cancer cells by being anchored with a specific antibody. Ion-doped melanin nanoparticles were found to have high bioavailability with long-term stability in solution, without any cytotoxicity in both in vitro and in vivo systems. By combining different imaging modalities with melanin particles, we can use the complexes to obtain faster diagnoses by computed tomography deep-body imaging and greater detailed pathological diagnostic information by magnetic resonance imaging. The ion-doped melanin nanoparticles also have applications for radio-diagnostic treatment and radio imaging-guided surgery, warranting further proof of concept experimental.

  18. Characteristics of solar and heliospheric ion populations observed near earth

    NASA Technical Reports Server (NTRS)

    Gloeckler, G.

    1984-01-01

    The composition and spectra of ions in solar-energetic-particle and energetic-storm-particle events, of diffuse ions upstream of the earth bow shock, and of ions in deep-geomagnetic-tail plasmoids are characterized in a summary of in situ observations. Data are presented in graphs and tables, and remarkable similarities are noted in the distribution functions of the heliospheric ion populations. The solar wind, acting through acceleration mechanisms associated with shocks and turbulence, is identified as the major plasma source of suprathermal and energetic particles.

  19. Effect of silica surface coating on the luminescence lifetime and upconversion temperature sensing properties of semiconductor zinc oxide doped with gallium(III) and sensitized with rare earth ions Yb(III) and Tm(III).

    PubMed

    Li, Yuemei; Li, Yongmei; Wang, Rui; Zheng, Wei

    2018-02-26

    Optical sensing of temperature by measurement of the ratio of the intensities of the 700 nm emission and the 800 nm emission of Ga(III)-doped ZnO (GZO) nanoparticles (NPs) and of GZO NPs coated with a silica shell are demonstrated at 980 nm excitation. It is found that the relative sensitivity of SiO 2 @Yb/Tm/GZO is 6.2% K -1 at a temperature of 693 K. This is ~3.4 times higher than that of Yb/Tm/GZO NPs. Obviously, the SiO 2 shell structure decreases the rate of the nonradiative decay. The decay time of the 800 nm emission of the Yb/Tm/GZO NPs (15 mol% Ga; 7 mol% Yb; 0.5 mol% Tm) displays a biexponential decay with a dominant decay time of 148 μs and a second decay time of ~412 μs. The lifetime of the Yb/Tm/GZO NPs at 293 K, and of the SiO 2 @Yb/Tm/GZO NPs are ~412 μs. Both the Yb/Tm/GZO and SiO 2 @Yb/Tm/GZO can be used up to 693 K. These results indicate that the SiO 2 shell on the Yb/Tm/GZO is beneficial in terms of sensitivity and resolution. Graphical abstract The enhancement the decay time and thermal sensitivity in the SiO 2 @Yb/Tm/GZO shell@core structure have been studied compared to the Ga(III)-doped Yb/Tm-doped ZnO (Yb/Tm/GZO). The SiO 2 @Yb/Tm/GZO have good thermal accuracy up to 693 °C.

  20. Structure-property-composition relationships in doped zinc oxides: enhanced photocatalytic activity with rare earth dopants.

    PubMed

    Goodall, Josephine B M; Illsley, Derek; Lines, Robert; Makwana, Neel M; Darr, Jawwad A

    2015-02-09

    In this paper, we demonstrate the use of continuous hydrothermal flow synthesis (CHFS) technology to rapidly produce a library of 56 crystalline (doped) zinc oxide nanopowders and two undoped samples, each with different particle properties. Each sample was produced in series from the mixing of an aqueous stream of basic zinc nitrate (and dopant ion or modifier) solution with a flow of superheated water (at 450 °C and 24.1 MPa), whereupon a crystalline nanoparticle slurry was rapidly formed. Each composition was collected in series, cleaned, freeze-dried, and then characterized using analytical methods, including powder X-ray diffraction, transmission electron microscopy, Brunauer-Emmett-Teller surface area measurement, X-ray photoelectron spectroscopy, and UV-vis spectrophotometry. Photocatalytic activity of the samples toward the decolorization of methylene blue dye was assessed, and the results revealed that transition metal dopants tended to reduce the photoactivity while rare earth ions, in general, increased the photocatalytic activity. In general, low dopant concentrations were more beneficial to having greater photodecolorization in all cases.

  1. Facile Synthesis of Pre-Doping Lithium-Ion Into Nitrogen-Doped Graphite Negative Electrode for Lithium-Ion Capacitor.

    PubMed

    Lee, Seul-Yi; Kim, Ji-Il; Rhee, Kyong Yop; Park, Soo-Jin

    2015-09-01

    Nitrogen-doped graphite, prepared via the thermal decomposition of melamine into a carbon matrix for use as the negative electrode in lithium-ion capacitors (LICs), was evaluated by electrochemical measurements. Furthermore, in order to study the performance of pre-doped lithium components as a function of nitrogen-doped material, the pre-doped lithium graphite was allowed to react with a lithium salt solution. The results showed that the nitrogen functional groups in the graphite largely influenced the pre-doped lithium components, thereby contributing to the discharge capacity and cycling performance. We confirmed that the large initial irreversible capacity could be significantly decreased by using pre-doped lithium components obtained through the nitrogen-doping method.

  2. Solar heavy ion Heinrich fluence spectrum at low earth orbit.

    PubMed

    Croley, D R; Spitale, G C

    1998-01-01

    Solar heavy ions from the JPL Solar Heavy Ion Model have been transported into low earth orbit using the Schulz cutoff criterion for L-shell access by ions of a specific charge to mass ratio. The NASA Brouwer orbit generator was used to get L values along the orbit at 60 second time intervals. Heavy ion fluences of ions 2 < or = Z < or = 92 have been determined for the LET range 1 to 130 MeV-cm2/mg by 60, 120 or 250 mils of aluminum over a period of 24 hours in a 425 km circular orbit inclined 51 degrees. The ion fluence is time dependent in the sense that the position of the spacecraft in the orbit at the flare onset time fixes the relationship between particle flux and spacecraft passage through high L-values where particles have access to the spacecraft.

  3. Synthesis, characterization and processing of active rare earth-doped chalcohalide glasses

    NASA Astrophysics Data System (ADS)

    Debari, Roberto Mauro

    Applications for infrared-transmitting non-oxide glass fibers span a broad range of topics. They can be used in the military, the medical field, telecommunications, and even in agriculture. Rare earth ions are used as dopants in these glasses in order to stimulate emissions in the infrared spectral region. In order to extend the host glass transmission further into the infrared, selenium atoms were substituted for sulfur in the established Ge-S-I chalcohalide glass system and the fundamental properties of these latter glasses were explored. Over 30 different compositions in the Ge-Se-I glass system were investigated as to their thermal and optical properties. The resulting optimum host with a composition of Ge15Se80I5 has a broad transmission range from 0.7 mum to 17.0 mum and a high working range over 145°C. The host glass also exhibited a Tg of 125°C, making rotational casting of a cladding tube for rod-and-tube fiberization a possibility. The base glass was doped with 1000 to 4000 ppm/wt of erbium, dysprosium, or neodymium. When doped with Er3+-ions, absorptions at 1.54 mum and 3.42 mum were observed. Nd3+-doping resulted in an absorption peak near 4.24 mum and Dy3+ ions caused absorption at 1.30 mum. Fluorescence emissions were found for neodymium at 1.396 mum with a FWHM of 74 nm, and for dysprosium at 1.145 mum with a FWHM of 75 nm, at 1.360 mum with a FWHM of 98 rim and at 1.674 mum with a FWHM of 60 nm. High optical quality tubes of the host glass could be formed using rotational casting in silica ampoules. Glass tubes, 4 to 6 cm long with a 1 cm outer diameter and a tailored inner-hole diameter ranging from 0.4 to 0.6 cm could be synthesized by this process with excellent dimensional tolerances around the circumference as well as along the length. A preform of this size provided 25 continuous meters of unclad fiber with diameters ranging from 140 to 200 mum. A UV-curable acrylate cladding was applied via an external coating cup. An x-ray analysis of the

  4. Effect of Rare Earth Ions on the Properties of Composites Composed of Ethylene Vinyl Acetate Copolymer and Layered Double Hydroxides

    PubMed Central

    Wang, Lili; Li, Bin; Zhao, Xiaohong; Chen, Chunxia; Cao, Jingjing

    2012-01-01

    Background The study on the rare earth (RE)-doped layered double hydroxides (LDHs) has received considerable attention due to their potential applications in catalysts. However, the use of RE-doped LDHs as polymer halogen-free flame retardants was seldom investigated. Furthermore, the effect of rare earth elements on the hydrophobicity of LDHs materials and the compatibility of LDHs/polymer composite has seldom been reported. Methodology/Principal Findings The stearate sodium surface modified Ni-containing LDHs and RE-doped Ni-containing LDHs were rapidly synthesized by a coprecipitation method coupled with the microwave hydrothermal treatment. The influences of trace amounts of rare earth ions La, Ce and Nd on the amount of water molecules, the crystallinity, the morphology, the hydrophobicity of modified Ni-containing LDHs and the adsorption of modifier in the surface of LDHs were investigated by TGA, XRD, TEM, contact angle and IR, respectively. Moreover, the effects of the rare earth ions on the interfacial compatibility, the flame retardancy and the mechanical properties of ethylene vinyl acetate copolymer (EVA)/LDHs composites were also explored in detail. Conclusions/Significance S-Ni0.1MgAl-La displayed more uniform dispersion and better interfacial compatibility in EVA matrix compared with other LDHs. Furthermore, the S-Ni0.1MgAl-La/EVA composite showed the best fire retardancy and mechanical properties in all composites. PMID:22693627

  5. CONDUCTION ELECTRON-MAGNETIC ION INTERACTION IN RARE EARTHS

    SciT

    Anderson, G.S.; Legvold, S.

    1958-11-01

    The proposal is maade that there is an additional effective electron- electron interaction in the rare earths which results from the conduction electron-magnetic ion exchange. The strength of the net electron-electron interaction should tnen be expected to be a function of spin as well as solute concentrations. (W.D.M.)

  6. Interfacing superconducting qubits and telecom photons via a rare-earth-doped crystal.

    PubMed

    O'Brien, Christopher; Lauk, Nikolai; Blum, Susanne; Morigi, Giovanna; Fleischhauer, Michael

    2014-08-08

    We propose a scheme to couple short single photon pulses to superconducting qubits. An optical photon is first absorbed into an inhomogeneously broadened rare-earth doped crystal using controlled reversible inhomogeneous broadening. The optical excitation is then mapped into a spin state using a series of π pulses and subsequently transferred to a superconducting qubit via a microwave cavity. To overcome the intrinsic and engineered inhomogeneous broadening of the optical and spin transitions in rare-earth doped crystals, we make use of a special transfer protocol using staggered π pulses. We predict total transfer efficiencies on the order of 90%.

  7. Homojunction silicon solar cells doping by ion implantation

    NASA Astrophysics Data System (ADS)

    Milési, Frédéric; Coig, Marianne; Lerat, Jean-François; Desrues, Thibaut; Le Perchec, Jérôme; Lanterne, Adeline; Lachal, Laurent; Mazen, Frédéric

    2017-10-01

    Production costs and energy efficiency are the main priorities for the photovoltaic (PV) industry (COP21 conclusions). To lower costs and increase efficiency, we are proposing to reduce the number of processing steps involved in the manufacture of N-type Passivated Rear Totally Diffused (PERT) silicon solar cells. Replacing the conventional thermal diffusion doping steps by ion implantation followed by thermal annealing allows reducing the number of steps from 7 to 3 while maintaining similar efficiency. This alternative approach was investigated in the present work. Beamline and plasma immersion ion implantation (BLII and PIII) methods were used to insert n-(phosphorus) and p-type (boron) dopants into the Si substrate. With higher throughput and lower costs, PIII is a better candidate for the photovoltaic industry, compared to BL. However, the optimization of the plasma conditions is demanding and more complex than the beamline approach. Subsequent annealing was performed on selected samples to activate the dopants on both sides of the solar cell. Two annealing methods were investigated: soak and spike thermal annealing. Best performing solar cells, showing a PV efficiency of about 20%, was obtained using spike annealing with adapted ion implantation conditions.

  8. Direct quantification of rare earth doped titania nanoparticles in individual human cells

    NASA Astrophysics Data System (ADS)

    Jeynes, J. C. G.; Jeynes, C.; Palitsin, V.; Townley, H. E.

    2016-07-01

    There are many possible biomedical applications for titania nanoparticles (NPs) doped with rare earth elements (REEs), from dose enhancement and diagnostic imaging in radiotherapy, to biosensing. However, there are concerns that the NPs could disintegrate in the body thus releasing toxic REE ions to undesired locations. As a first step, we investigate how accurately the Ti/REE ratio from the NPs can be measured inside human cells. A quantitative analysis of whole, unsectioned, individual human cells was performed using proton microprobe elemental microscopy. This method is unique in being able to quantitatively analyse all the elements in an unsectioned individual cell with micron resolution, while also scanning large fields of view. We compared the Ti/REE signal inside cells to NPs that were outside the cells, non-specifically absorbed onto the polypropylene substrate. We show that the REE signal in individual cells co-localises with the titanium signal, indicating that the NPs have remained intact. Within the uncertainty of the measurement, there is no difference between the Ti/REE ratio inside and outside the cells. Interestingly, we also show that there is considerable variation in the uptake of the NPs from cell-to-cell, by a factor of more than 10. We conclude that the NPs enter the cells and remain intact. The large heterogeneity in NP concentrations from cell-to-cell should be considered if they are to be used therapeutically.

  9. Short wavelength ion waves upstream of the earth's bow shock

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Gurnett, D. A.

    1984-01-01

    The identification and explanation of short wavelength antenna interference effects observed in spacecraft plasma wave data have provided an important new method of determining limits on the wavelength, direction of propagation, and Doppler shift of short wavelength electrostatic waves. Using the ISEE-1 wideband electric field data, antenna interference effects have been identified in the ion waves upstream of the earth's bow shock. This identification implies that wavelengths of the upstream ion waves are shorter than the antenna length. The interference effects also provide new measurements of the direction of propagation of the ion waves. The new measurements show that the wave vectors of the ion waves are not parallel to the interplanetary magnetic field (IMF) as previously reported. The direction of propagation does not appear to be controlled by the IMF. In addition, analysis of the Doppler shift of the short wavelength ion waves has provided a measurement of the dispersion relation. The upper limit of the rest frame frequency was found to be on the order of the ion plasma frequency. At this frequency, the wavelength is on the order of a few times the Debye length. The results of this study now provide strong evidence that the ion waves in the upstream region are Doppler-shifted ion acoustic waves. Previously announced in STAR as N83-36328

  10. Rare Earth Doped GaN Laser Structures Using Metal Modulated Epitaxy

    DTIC Science & Technology

    2015-03-30

    from Eu-doped GaN,” Appl. Phys. Lett., vol. 75, pp. 1189–1191, 1999. 24. D. S . Lee and A. J. Steckl, “Room-temperature-grown rare- earth -doped GaN...luminescent thin films,” Appl. Phys. Lett., vol. 79, pp. 1962–1964,2001. 25. D. S . Lee and A. J. Steckl, “Lateral color integration on rare- earth doped... s . 0.259nm/ s =1.14E13cm-2/ s =1 ML/ s .Our plasma source was optimized to work at 1.5 sccm and 230 W RF power and it provides a growth rate of 0.8 ML/ s

  11. The ion temperature gradient: An intrinsic property of Earth's magnetotail

    NASA Astrophysics Data System (ADS)

    Lu, San; Artemyev, A. V.; Angelopoulos, V.; Lin, Y.; Wang, X. Y.

    2017-08-01

    Although the ion temperature gradient along (XGSM) and across (ZGSM) the Earth's magnetotail, which plays a key role in generating the cross-tail current and establishing pressure balance with the lobes, has been extensively observed by spacecraft, the mechanism responsible for its formation is still unknown. We use multispacecraft observations and three-dimensional (3-D) global hybrid simulations to reveal this mechanism. Using THEMIS (Time History of Events and Macroscale Interactions during Substorms), Geotail, and ARTEMIS (Acceleration, Reconnection, Turbulence and Electrodynamics of Moon's Interaction with the Sun) observations during individual, near-simultaneous plasma sheet crossings from 10 to 60 RE, we demonstrate that the ion temperature ZGSM profile is bell-shaped at different geocentric distances. This ZGSM profile is also prevalent in statistics of 200 THEMIS current sheet crossings in the near-Earth region. Using 3-D global hybrid simulations, we show that mapping of the XGSM gradient of ion temperature along magnetic field lines produces such a bell-shaped profile. The ion temperature mapping along magnetic field lines in the magnetotail enables construction of two-dimensional distributions of these quantities from vertical (north-south) spacecraft crossings. Our findings suggest that the ion temperature gradient is an intrinsic property of the magnetotail that should be considered in kinetic descriptions of the magnetotail current sheet. Toward this goal, we use theoretical approaches to incorporate the temperature gradient into kinetic current sheet models, making them more realistic.

  12. Microstructural and electrical characteristics of rare earth oxides doped ZnO varistor films

    NASA Astrophysics Data System (ADS)

    Jiao, Lei; Mei, Yunzhu; Xu, Dong; Zhong, Sujuan; Ma, Jia; Zhang, Lei; Bao, Li

    2018-02-01

    ZnO-Bi2O3 varistor films doped with two kinds of rare earth element oxides (Lu2O3 and Yb2O3) were prepared by the sol-gel method. The effects of Lu2O3/Yb2O3 doping on the microstructure and electrical characteristics of ZnO-Bi2O3 varistor films were investigated. All samples show a homogenized morphology and an improved nonlinear relationship between the electric field (E) and current density (I). Both Yb2O3 and Lu2O3 doping can decrease the grain size of ZnO-Bi2O3 varistor films and improve the electrical properties, which have a positive effect on the development of ZnO varistor ceramics. Yb2O3 doping significantly increases the dielectric constant at low frequency. 0.2 mol. % Yb2O3 doped ZnO-Bi2O3 varistor films exhibit the highest nonlinear coefficient (2.5) and the lowest leakage current (328 μA) among Lu2O3/Yb2O3 doped ZnO-Bi2O3 varistor films. Similarly, 0.1 mol. % Lu2O3 doping increases the nonlinear coefficient to 1.9 and decrease the leakage current to 462 μA.

  13. Optical Properties of Nd Doped Rare Earth Vanadates (Preprint)

    DTIC Science & Technology

    2010-07-01

    Rare earth orthovanadates are being used as substitute for traditional solid state laser hosts such as yttrium aluminium garnet (YAG). While the most...common of these is yttrium orthovanadate, other rare earth vanadates such as lutetium vanadate and gadolinium vanadate are being used for their... gadolinium vanadate are being used for their special properties in certain applications. We report new measurements of the refractive indices and thermo

  14. Magnetic and magnetoelectric properties of NdCrTiO5 revealed by systematically rare-earth doping

    NASA Astrophysics Data System (ADS)

    Li, Qing; Feng, Zhenjie; Cheng, Cheng; Wang, Bojie; Chu, Hao; Huang, Ping; Wang, Difei; Qian, Xiaolong; Yu, Chuan; Wang, Guohua; Deng, Dongmei; Jing, Chao; Cao, Shixun; Zhang, Jincang

    2018-01-01

    We have systematically synthesized polycrystalline samples of Nd0.9A0.1CrTiO5 (A = Pr, Nd, Gd, Dy, Er, Tm, and Yb), and have investigated their crystal structure, polarization and magnetic susceptibility. The polarization values of doped samples are suppressed comparing to pure NdCrTiO5 sample, which indicates that the polarization is highly dependence with the magnetic moments of doping ions. The TN of Cr-Cr in Nd0.9A0.1CrTiO5 are dominated by both the suppression effect caused by doped magnetic moment increment and the enhancement effect caused by c axis contracting. We conclude that the magnetic moments in the rare-earth Nd sites play an important role in the magnetoelectric effect in NdCrTiO5 family. The substitution effect discussion here can help us well understand the intrinsic mechanism and provide a possible guidance in exploring new magnetoelectric coupling systems.

  15. Distribution coefficients of rare earth ions in cubic zirconium dioxide

    NASA Astrophysics Data System (ADS)

    Romer, H.; Luther, K.-D.; Assmus, W.

    1994-08-01

    Cubic zirconium dioxide crystals are grown with the skull melting technique. The effective distribution coefficients for Nd(exp 3+), Sm(exp 3+) and Er(sup 3+) as dopants are determined experimentally as a function of the crystal growth velocity. With the Burton-Prim-Slichter theory, the equilibrium distribution coefficients can be calculated. The distribution coefficients of all other trivalent rare earth ions can be estimated by applying the correlation towards the ionic radii.

  16. The influence of different alkaline earth oxides on the structural and optical properties of undoped, Ce-doped, Sm-doped, and Sm/Ce co-doped lithium alumino-phosphate glasses

    NASA Astrophysics Data System (ADS)

    Othman, H. A.; Arzumanyan, G. M.; Möncke, D.

    2016-12-01

    Undoped, singly Sm doped, Ce doped, and Sm/Ce co-doped lithium alumino-phosphate glasses with different alkaline earth modifiers were prepared by melt quenching. The structure of the prepared glasses was investigated by FT-IR and Raman, as well as by optical spectroscopy. The effect of the optical basicity of the host glass matrix on the added active dopants was studied, as was the effect doping had on the phosphate structural units. The optical edge shifts toward higher wavelengths with an increase in the optical basicity due to the increased polarizability of the glass matrix, but also with increasing CeO2 concentration as a result of Ce3+/Ce4+ inter valence charge transfer (IV-CT) absorption. The optical band gap for direct and indirect allowed transitions was calculated for the undoped glasses. The glass sample containing Mg2+ modifier ions is found to have the highest value (4.16 eV) for the optical band gap while Ba2+ has the lowest value (3.61 eV). The change in the optical band gap arises from the structural changes and the overall polarizability (optical basicity). Refractive index, molar refractivity Rm and molar polarizability αm values increase with increasing optical basicity of the glasses. The characteristic absorption peaks of Sm3+ were also investigated. For Sm/Ce co-doped glasses, especially at high concentration of CeO2, the absorption of Ce3+ hinders the high energy absorption of Sm3+ and this effect becomes more obvious with increasing optical basicity.

  17. Rare-earth-doped materials with application to optical signal processing, quantum information science, and medical imaging technology

    NASA Astrophysics Data System (ADS)

    Cone, R. L.; Thiel, C. W.; Sun, Y.; Böttger, Thomas; Macfarlane, R. M.

    2012-02-01

    Unique spectroscopic properties of isolated rare earth ions in solids offer optical linewidths rivaling those of trapped single atoms and enable a variety of recent applications. We design rare-earth-doped crystals, ceramics, and fibers with persistent or transient "spectral hole" recording properties for applications including high-bandwidth optical signal processing where light and our solids replace the high-bandwidth portion of the electronics; quantum cryptography and information science including the goal of storage and recall of single photons; and medical imaging technology for the 700-900 nm therapeutic window. Ease of optically manipulating rare-earth ions in solids enables capturing complex spectral information in 105 to 108 frequency bins. Combining spatial holography and spectral hole burning provides a capability for processing high-bandwidth RF and optical signals with sub-MHz spectral resolution and bandwidths of tens to hundreds of GHz for applications including range-Doppler radar and high bandwidth RF spectral analysis. Simply stated, one can think of these crystals as holographic recording media capable of distinguishing up to 108 different colors. Ultra-narrow spectral holes also serve as a vibration-insensitive sub-kHz frequency reference for laser frequency stabilization to a part in 1013 over tens of milliseconds. The unusual properties and applications of spectral hole burning of rare earth ions in optical materials are reviewed. Experimental results on the promising Tm3+:LiNbO3 material system are presented and discussed for medical imaging applications. Finally, a new application of these materials as dynamic optical filters for laser noise suppression is discussed along with experimental demonstrations and theoretical modeling of the process.

  18. Spectroscopic studies of Dy3+ ion doped tellurite glasses for solid state lasers and white LEDs.

    PubMed

    V, Himamaheswara Rao; P, Syam Prasad; M, Mohan Babu; P, Venkateswara Rao; T, Satyanarayana; Luís F, Santos; N, Veeraiah

    2018-01-05

    Rare earth ion Dy 3+ -doped tellurite glasses were synthesised in the system of (75-x)TeO 2 -15Sb 2 O 3 -10WO 3 -xDy 2 O 3 (TSWD glasses). XRD and FTIR characterizations were used to find the crystalline and structural properties. The intensities of the electronic transitions and the ligand environment around the Dy 3+ ion were determined using the Judd-Ofelt (J-O) theory on the absorption spectra of the glasses. The measured luminescence spectra exhibit intense emissions at 574 and 484nm along with less intense emissions around 662 and 751nm. Various radiative properties of the 4 F 9/2 excited level of Dy 3+ ion were calculated for the glasses. Decay profiles were measured to find the life times and quantum efficiencies. Yellow to blue intensity ratio (Y/B), CIE chromaticity coordinates and correlated color temperature (CCT) values are calculated using the emission spectra to evaluate the emitted light. The obtained results suggest the utility of the glasses for potential yellow laser and white LED's applications. Copyright © 2017 Elsevier B.V. All rights reserved.

  19. Spectroscopic studies of Dy3 + ion doped tellurite glasses for solid state lasers and white LEDs

    NASA Astrophysics Data System (ADS)

    Himamaheswara Rao, V.; Syam Prasad, P.; Mohan Babu, M.; Venkateswara Rao, P.; Satyanarayana, T.; Luís F., Santos; Veeraiah, N.

    2018-01-01

    Rare earth ion Dy3 +-doped tellurite glasses were synthesised in the system of (75-x)TeO2-15Sb2O3-10WO3-xDy2O3 (TSWD glasses). XRD and FTIR characterizations were used to find the crystalline and structural properties. The intensities of the electronic transitions and the ligand environment around the Dy3 + ion were determined using the Judd-Ofelt (J-O) theory on the absorption spectra of the glasses. The measured luminescence spectra exhibit intense emissions at 574 and 484 nm along with less intense emissions around 662 and 751 nm. Various radiative properties of the 4F9/2 excited level of Dy3 + ion were calculated for the glasses. Decay profiles were measured to find the life times and quantum efficiencies. Yellow to blue intensity ratio (Y/B), CIE chromaticity coordinates and correlated color temperature (CCT) values are calculated using the emission spectra to evaluate the emitted light. The obtained results suggest the utility of the glasses for potential yellow laser and white LED's applications.

  20. Electron magnetic reconnection without ion coupling in Earth's turbulent magnetosheath.

    PubMed

    Phan, T D; Eastwood, J P; Shay, M A; Drake, J F; Sonnerup, B U Ö; Fujimoto, M; Cassak, P A; Øieroset, M; Burch, J L; Torbert, R B; Rager, A C; Dorelli, J C; Gershman, D J; Pollock, C; Pyakurel, P S; Haggerty, C C; Khotyaintsev, Y; Lavraud, B; Saito, Y; Oka, M; Ergun, R E; Retino, A; Le Contel, O; Argall, M R; Giles, B L; Moore, T E; Wilder, F D; Strangeway, R J; Russell, C T; Lindqvist, P A; Magnes, W

    2018-05-01

    Magnetic reconnection in current sheets is a magnetic-to-particle energy conversion process that is fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron-scale diffusion region 1,2 . On larger scales, ions couple to the newly reconnected magnetic-field lines and are ejected away from the diffusion region in the form of bi-directional ion jets at the ion Alfvén speed 3-5 . Much of the energy conversion occurs in spatially extended ion exhausts downstream of the diffusion region 6 . In turbulent plasmas, which contain a large number of small-scale current sheets, reconnection has long been suggested to have a major role in the dissipation of turbulent energy at kinetic scales 7-11 . However, evidence for reconnection plasma jetting in small-scale turbulent plasmas has so far been lacking. Here we report observations made in Earth's turbulent magnetosheath region (downstream of the bow shock) of an electron-scale current sheet in which diverging bi-directional super-ion-Alfvénic electron jets, parallel electric fields and enhanced magnetic-to-particle energy conversion were detected. Contrary to the standard model of reconnection, the thin reconnecting current sheet was not embedded in a wider ion-scale current layer and no ion jets were detected. Observations of this and other similar, but unidirectional, electron jet events without signatures of ion reconnection reveal a form of reconnection that can drive turbulent energy transfer and dissipation in electron-scale current sheets without ion coupling.

  1. Electron magnetic reconnection without ion coupling in Earth's turbulent magnetosheath

    NASA Astrophysics Data System (ADS)

    Phan, T. D.; Eastwood, J. P.; Shay, M. A.; Drake, J. F.; Sonnerup, B. U. Ö.; Fujimoto, M.; Cassak, P. A.; Øieroset, M.; Burch, J. L.; Torbert, R. B.; Rager, A. C.; Dorelli, J. C.; Gershman, D. J.; Pollock, C.; Pyakurel, P. S.; Haggerty, C. C.; Khotyaintsev, Y.; Lavraud, B.; Saito, Y.; Oka, M.; Ergun, R. E.; Retino, A.; Le Contel, O.; Argall, M. R.; Giles, B. L.; Moore, T. E.; Wilder, F. D.; Strangeway, R. J.; Russell, C. T.; Lindqvist, P. A.; Magnes, W.

    2018-05-01

    Magnetic reconnection in current sheets is a magnetic-to-particle energy conversion process that is fundamental to many space and laboratory plasma systems. In the standard model of reconnection, this process occurs in a minuscule electron-scale diffusion region1,2. On larger scales, ions couple to the newly reconnected magnetic-field lines and are ejected away from the diffusion region in the form of bi-directional ion jets at the ion Alfvén speed3-5. Much of the energy conversion occurs in spatially extended ion exhausts downstream of the diffusion region6. In turbulent plasmas, which contain a large number of small-scale current sheets, reconnection has long been suggested to have a major role in the dissipation of turbulent energy at kinetic scales7-11. However, evidence for reconnection plasma jetting in small-scale turbulent plasmas has so far been lacking. Here we report observations made in Earth's turbulent magnetosheath region (downstream of the bow shock) of an electron-scale current sheet in which diverging bi-directional super-ion-Alfvénic electron jets, parallel electric fields and enhanced magnetic-to-particle energy conversion were detected. Contrary to the standard model of reconnection, the thin reconnecting current sheet was not embedded in a wider ion-scale current layer and no ion jets were detected. Observations of this and other similar, but unidirectional, electron jet events without signatures of ion reconnection reveal a form of reconnection that can drive turbulent energy transfer and dissipation in electron-scale current sheets without ion coupling.

  2. Quantum light storage in rare-earth-ion-doped solids

    NASA Astrophysics Data System (ADS)

    Hua, Yi-Lin; Zhou, Zong-Quan; Li, Chuan-Feng; Guo, Guang-Can

    2018-02-01

    Not Available Project supported by the National Key Research and Development Program of China (Grant No. 2017YFA0304100), the National Natural Science Foundation of China (Grant Nos. 61327901, 11774331, 11774335, 11504362, 11325419, and 11654002), the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (Grant No. QYZDY-SSW-SLH003), and the Fundamental Research Funds for the Central Universities, China (Grant Nos. WK2470000023 and WK2470000026).

  3. Determination of theoretical capacity of metal ion-doped LiMn 2O 4 as the positive electrode in Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Todorov, Yanko M.; Hideshima, Yasufumi; Noguchi, Hideyuki; Yoshio, Masaki

    The theoretical capacity and cation vacancy of metal ion (M)-doped LiMn 2- xM xO 4 spinel compounds serving as positive electrodes in a 4-V lithium ion batteries are calculated. The capacity depends strongly on the mole fraction of doped metal ion and vacancies. The theoretical capacity increases with increasing oxidation number of the doped metal ion in the 16d site of LiMn 2O 4 at the same doping fraction. The validity of the proposed equation for calculation of the capacity has been initially confirmed using a metal ion with well-known valence, such as the Al ion. The oxidation state of Co, Ni and Cr ions in the spinel structure is found to be trivalent, divalent and trivalent, respectively. Analysis shows that metal ion-doped spinel compounds with low vacancy content promote high capacity.

  4. Stabilization of Phase IV in CexLa1-xB6 (x=0.4, 0.5) by Pr and Nd Ion Dopings

    NASA Astrophysics Data System (ADS)

    Kondo, Akihiro; Taniguchi, Toshihiro; Tanida, Hiroshi; Matsumura, Takeshi; Sera, Masafumi; Iga, Fumitoshi; Tou, Hideki; Sakakibara, Toshiro; Kunii, Satoru

    2009-09-01

    We have studied the effect of magnetic rare-earth ion (Pr, Nd) doping on phase IV in CexLa1-xB6 (x=0.4, 0.5) systems. An unexpected large increase in the IV-I transition temperature TIV--I by Pr and Nd dopings was observed, while no such increase was observed for x≥ 0.6. Although we do not know the reason why the doping effect markedly differs between x≤ 0.5 and x≥ 0.6 at present, the order parameter in phase IV for x≤ 0.5 is coupled with the magnetic dipole moment of Pr and Nd ions and phase IV is stabilized.

  5. Rare earth doped M-type hexaferrites; ferromagnetic resonance and magnetization dynamics

    NASA Astrophysics Data System (ADS)

    Sharma, Vipul; Kumari, Shweta; Kuanr, Bijoy K.

    2018-05-01

    M-type hexagonal barium ferrites come in the category of magnetic material that plays a key role in electromagnetic wave propagation in various microwave devices. Due to their large magnetic anisotropy and large magnetization, their operating frequency exceeds above 50 GHz. Doping is a way to vary its magnetic properties to such an extent that its ferromagnetic resonance (FMR) response can be tuned over a broad frequency band. We have done a complete FMR study of rare earth elements neodymium (Nd) and samarium (Sm), with cobalt (Co) as base, doped hexaferrite nanoparticles (NPs). X-ray diffractometry, vibrating sample magnetometer (VSM), and ferromagnetic resonance (FMR) techniques were used to characterize the microstructure and magnetic properties of doped hexaferrite nanoparticles. Using proper theoretical electromagnetic models, various parameters are extracted from FMR data which play important role in designing and fabricating high-frequency microwave devices.

  6. Synthesis and spectral characterizations of trivalent ions (Cr3+, Fe3+) doped CdO nanopowders

    NASA Astrophysics Data System (ADS)

    Aswani, T.; Babu, B.; Pushpa Manjari, V.; Joyce Stella, R.; Thirumala Rao, G.; Rama Krishna, Ch.; Ravikumar, R. V. S. S. N.

    2014-03-01

    Trivalent transition metal ions (Cr3+, Fe3+) doped CdO nanopowders via sonication in the presence of Sodium lauryl sulfate as stabilizing agent were synthesized and characterized. Powder XRD studies indicate that the obtained CdO has a cubic phase and concluded that the trivalent ions doping induced the lattice constants to change some extent. Optical absorption spectra exhibited the characteristic bands of Cr3+ and Fe3+ ions in octahedral site symmetry. Crystal field (Dq) and inter-electronic repulsion (B and C) parameters are evaluated for Cr3+ doped CdO nanopowders as Dq = 1540, B = 619 and C = 3327 cm-1 and for Fe3+ doped CdO nanopowders Dq = 920, B = 690, C = 2750 cm-1. EPR spectra of the Cr3+ and Fe3+ doped CdO nanopowders exhibited resonances at g = 1.973 and g = 2 respectively which indicate distorted octahedral site for both ions with the host. Photoluminescence spectra shows the emission bands in violet and bluish green regions for Cr3+ doped CdO, ultraviolet and blue emissions for Fe3+ doped CdO nanopowders. The CIE chromaticity coordinates were also evaluated from the emission spectrum. FT-IR spectra indicate the presence of various functional groups of host lattice.

  7. Memristive Ion Channel-Doped Biomembranes as Synaptic Mimics.

    PubMed

    Najem, Joseph S; Taylor, Graham J; Weiss, Ryan J; Hasan, Md Sakib; Rose, Garrett; Schuman, Catherine D; Belianinov, Alex; Collier, C Patrick; Sarles, Stephen A

    2018-05-22

    Solid-state neuromorphic systems based on transistors or memristors have yet to achieve the interconnectivity, performance, and energy efficiency of the brain due to excessive noise, undesirable material properties, and nonbiological switching mechanisms. Here we demonstrate that an alamethicin-doped, synthetic biomembrane exhibits memristive behavior, emulates key synaptic functions including paired-pulse facilitation and depression, and enables learning and computing. Unlike state-of-the-art devices, our two-terminal, biomolecular memristor features similar structure (biomembrane), switching mechanism (ion channels), and ionic transport modality as biological synapses while operating at considerably lower power. The reversible and volatile voltage-driven insertion of alamethicin peptides into an insulating lipid bilayer creates conductive pathways that exhibit pinched current-voltage hysteresis at potentials above their insertion threshold. Moreover, the synapse-like dynamic properties of the biomolecular memristor allow for simplified learning circuit implementations. Low-power memristive devices based on stimuli-responsive biomolecules represent a major advance toward implementation of full synaptic functionality in neuromorphic hardware.

  8. PAL spectroscopy of rare-earth doped Ga-Ge-Te/Se glasses

    NASA Astrophysics Data System (ADS)

    Shpotyuk, Ya.; Ingram, A.; Shpotyuk, O.

    2016-04-01

    Positron annihilation lifetime (PAL) spectroscopy was applied for the first time to study free-volume void evolution in chalcogenide glasses of Ga-Ge-Te/Se cut-section exemplified by glassy Ga10Ge15Te75 and Ga10Ge15Te72Se3 doped with 500 ppm of Tb3+ or Pr3+. The collected PAL spectra reconstructed within two-state trapping model reveal decaying tendency in positron trapping efficiency in these glasses under rare-earth doping. This effect results in unchanged or slightly increased defect-related lifetimes τ2 at the cost of more strong decrease in I2 intensities, as well as reduced positron trapping rate in defects and fraction of trapped positrons. Observed changes are ascribed to rare-earth activated elimination of intrinsic free volumes associated mainly with negatively-charged states of chalcogen atoms especially those neighboring with Ga-based polyhedrons.

  9. Application of Laser Induced Breakdown Spectroscopy to Monitor Rare Earth Ions in Glass Matrix

    NASA Astrophysics Data System (ADS)

    Sharma, Prakash; Carter, Michael; Kumar, Akshaya

    2013-05-01

    The Laser Induced breakdown spectroscopy (LIBS) is a real time online technique that can be used to monitor the concentration of rare earth ions in amorphous glass matrix. This study has significant application in the glass industry where the composition of the glass can be monitored in real time using LIBS technology for quality control. The Eu3 + ions doped silicate glasses were developed via sol gel method. The glasses of varying molar percentages of Eu3 + (0.02, 0.05 and 0.08 mole percent), were prepared to study the effect of variation in concentration of Eu3 + ions on the LIBS signal and to calculate its limit of detection (LOD). The spectral assignment of the observed LIBS spectrum has been made. In order to find the maximum signal to noise ratio, we also recorded the intensity of LIBS signal for various integration start delay (ISD) time at a constant power of (pulsed Nd: YAG) laser. The ocean optics LIBS 2500plus spectrometer along with a Q switched Nd:YAG laser (Quantel, Big Sky) were used to record the LIBS spectrum.

  10. Rare-earth doped transparent nano-glass-ceramics: a new generation of photonic integrated devices

    NASA Astrophysics Data System (ADS)

    Rodríguez-Armas, Vicente Daniel; Tikhomirov, Victor K.; Méndez-Ramos, Jorge; Yanes, Angel C.; Del-Castillo, Javier; Furniss, David; Seddon, Angela B.

    2007-05-01

    We report on optical properties and prospect applications on rare-earth doped oxyfluoride precursor glass and ensuing nano-glass-ceramics. We find out the spectral optical gain of the nano-glass-ceramics and show that its flatness and breadth are advantageous as compared to contemporary used erbium doped optical amplifiers. We present the possibility of flat gain cross-section erbium doped waveguide amplifiers as short 'chip', all-optical, devices capable of dense wavelength division multiplexing, including the potential for direct writing of these devices inside bulk glasses for three-dimensional photonic integration. We carried out a comparative study of the up-conversion luminescence in Er 3+-doped and Yb 3+-Er 3+-Tm 3+ co-doped samples, which indicates that these materials can be used as green/red tuneable up-conversion phosphors and white light simulation respectively. Observed changes in the spectra of the up-conversion luminescence provide a tool for tuning the colour opening the way for producing 3-dimensional optical recording.

  11. Structural, optical absorption and photoluminescence spectral studies of Sm3+ ions in Alkaline-Earth Boro Tellurite glasses

    NASA Astrophysics Data System (ADS)

    Siva Rama Krishna Reddy, K.; Swapna, K.; Mahamuda, Sk.; Venkateswarlu, M.; Srinivas Prasad, M. V. V. K.; Rao, A. S.; Prakash, G. Vijaya

    2018-05-01

    Sm3+ ions doped Alkaline-Earth Boro Tellurite (AEBT) glasses were prepared by using conventional melt quenching technique and characterized using the spectroscopic techniques such as FT-IR, optical absorption, emission and decay spectral measurements to understand their utility in optoelectronic devices. From absorption spectra, the bonding parameters, nephelauxetic ratios were determined to know the nature of bonding between Sm3+ ions and its surrounding ligands. From the measured oscillator strengths, the Judd-Ofelt (J-O) intensity parameters were evaluated and in turn used to estimate various radiative parameters for the fluorescent levels of Sm3+ ions in AEBT glasses. The PL spectra of Sm3+ ions exhibit three emission bands corresponding to the transitions 4G5/2 → 6H5/2, 6H7/2 and 6H9/2 in the visible region for which the emission cross-sections and branching ratios were evaluated. The decay spectral profiles measured for 4G5/2 → 6H7/2 transition showed single exponential for lower concentration and non-exponential for higher concentration of doped rare earth ion in the as prepared glasses. Conversion of decay spectral profiles from single to non-exponential have been analyzed using Inokuti-Hirayama (I-H) model to understand the energy transfer mechanism involved in the decay process. CIE Chromaticity coordinates were measured using emission spectral data to identify the exact region of emission from the as-prepared glasses. From the evaluated radiative parameters, emission cross-sections and quantum efficiencies, it was observed that AEBT glass with 1 mol% of Sm3+ ions is more suitable for designing optoelectronic devices.

  12. Controlling the Photocorrosion of Zinc Sulfide Nanoparticles in Water by Doping with Chloride and Cobalt Ions.

    PubMed

    Weide, Philipp; Schulz, Katharina; Kaluza, Stefan; Rohe, Markus; Beranek, Radim; Muhler, Martin

    2016-12-06

    Photodegradation under UV light irradiation is a major drawback in photocatalytic applications of sulfide semiconductors. ZnS nanoparticles were doped with very low amounts of chloride or cobalt ions in the ppm range and codoped with chloride and cobalt ions during their synthesis by precipitation in aqueous solution followed by calcination. The high-temperature wurtzite phase annealed at 800 °C had a high susceptibility to UV irradiation in water, while the low-temperature zincblende phase annealed at 400 °C was found to be stable. Chlorine doping increased the rate of photocorrosion in water, whereas cobalt doping led to a stabilization of the ZnS nanoparticles. Based on photochemical and spectroscopic investigations applying UV/vis, X-ray photoelectron, and photoluminescence spectroscopy, the increased susceptibility of Cl-doped ZnS is ascribed to a higher number of surface point defects, whereas the stabilization by Co 2+ is caused by additional recombination pathways for the charge carriers in the bulk, thus avoiding photocorrosion processes at the surface. Additional doping of Cl-doped ZnS with cobalt ions was found to counteract the detrimental effect of the chloride ions efficiently.

  13. Origins of Energetic Ions in the Earth's Magnetosheath

    NASA Technical Reports Server (NTRS)

    Fuselter, S. A.; Shelley, E. G.; Klumpar, D. M.

    1992-01-01

    The analysis and interpretation of the combined scientific data from the Hot Plasma Composition Experiment (HPCE) and the Charge Energy Mass (CHEM) spectrometer on the Active Mesospheric Particle Tracer Experiment (AMPTE) Charge Composition Explorer (CCE) spacecraft are discussed. These combined data sets have and will be used to survey the energetic ion environment in the Earth's magnetosheath to determine the origins and relative strengths of the energetic ion populations found there. A computer code was developed to analyze and interpret the data sets. The focus of the first year was on the determination of the contribution of leaked magnetospheric protons to the total energetic proton population. Emphasis was placed on intervals when the AMPTE spacecraft was in the plasma depletion layer because it was argued that in this region, only the leaked population contributes to the energetic ion population. Manipulation of the CHEM data and comparison of the CHEM and HPCE data over their common energy range near the magnetopause also contributed directly to a second study of that region.

  14. The Transport of Solar Ions Through the Earth's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Lennartsson, O. W.

    1999-01-01

    This report covers the initial phase of an investigation that was originally selected by NASA Headquarters for funding by a grant but was later transferred to NASA GSFC for continued funding under a new and separate contract. The principal objective of the investigation, led by Dr. O.W. Lennartsson, is to extract information about the solar origin plasma in Earth's magnetosphere, specifically about the entry and transport of this plasma, using energetic (10 eV/e to 18 keV/e) ion composition data from the Lockheed Plasma Composition Experiment on the NASA/ESA International Sun-Earth Explorer One (ISEE 1) satellite. These data were acquired many years ago, from November 1977 through March of 1982, but, because of subsequent failures of similar experiments on several other spacecraft, they are still the only substantial ion composition data available from Earth's magnetotail, beyond 10 R(sub E), in the critically important sub-kev to keV energy range. All of the Lockheed data now exist in a compacted scientific format, suitable for large-scale statistical investigations, which has been archived both at Lockheed Martin in Palo Alto and at the National Space Science Data Center (NSSDC) in Greenbelt. The completion of the archiving, by processing the remaining half of the data, was made possible by separate funding through a temporary NASA program for data restoration and was given priority over the data analysis by a no-cost extension of the subject grant. By chance, the period of performance coincided with an international study of source and loss processes of magnetospheric plasma, sponsored by the International Space Science Institute (ISSI) in Bern, Switzerland, for which Dr. Lennartsson was invited to serve as one of 12 co-chairs. This study meshed well with the continued analysis of the NASA/Lockheed ISEE ion composition data and provided a natural forum for a broader discussion of the results from this unique experiment. What follows is arranged, for the most

  15. Lanthanide Contraction Effect In Magnetic Thermoelectric Materials Of Rare Earth-doped Bi1.5Pb0.5Ca2Co2O8

    NASA Astrophysics Data System (ADS)

    Sutjahja, Inge Magdalena; Akbar, Taufik; Nugroho, Agung

    2010-12-01

    We report in this paper the result of synthesis and crystal structure characterization of magnetic thermoelectric materials of rare-earth-doped Bi1.5Pb0.5Ca2Co2O8, namely Bi1.5Pb0.5Ca1.9RE0.1Co2O8 (RE = La, Pr, Sm, Eu, Gd, Ho). Single phase samples have been prepared by solid state reaction process using precursors of Bi2O3, PbO, CaCO3, RE2O3, and Co3O4. The precursors were pulverized, calcinated, and sintered in air at various temperatures for several hours. Analysis of XRD data shows that Bi1.5Pb0.5Ca1.9RE0.1Co2O8 compound is a layered system consisting of an alternate stack of CoO2 layer and Bi2Sr2O4 block along the c-axis. The misfit structure along b-direction is revealed from the difference of the b-axis length belonging to two sublattices, namely hexagonal CdI2-type CoO2 layer and rock-salt (RS) NaCl-type Bi2Sr2O4 block, while they possess the common a- and c-axis lattice parameters and β angles. The overall crystal structure parameters (a, b, and c) increases with type of doping from La to Ho, namely by decreasing the ionic radii of rare-earth ion. We discuss this phenomenon in terms of the lanthanide contraction, an effect commonly found in the rare-earth compound, results from poor shielding of nuclear charge by 4f electrons. In addition, the values of b-lattice parameters in these rare-earth doped samples are almost the same with those belongs to undoped parent compound (Bi1.5Pb0.5Sr2Co2O8) and its related Y-doped (Bi1.5Pb0.5Ca1.9Y0.1Co2O8) samples, while the c-values reduced significantly in rare-earth doped samples, with opposite trend with those of variation of a-axis length. Morevover, the misfit degree in rare-earth doped compound is higher in compared to parent compound and Y-doped samples. We argue that these structural changes induced by rare-earth doping may provide information for the variation of electronic structure of Co-ions (Co3+ and Co4+), in particular their different spin states of low-spin, intermediate-spin, and high-spin. This, in

  16. Effect of doping with nickel ions on the structural state of a zinc oxide crystal

    NASA Astrophysics Data System (ADS)

    Dubinin, S. F.; Sokolov, V. I.; Parkhomenko, V. D.; Maksimov, V. I.; Gruzdev, N. B.

    2009-10-01

    The fine structure of a hexagonal zinc oxide crystal doped with nickel ions of the composition Zn1 - x Ni x O has been studied using neutron diffraction and magnetic measurements. It is established that even at very low doping levels ( x = 0.0004), the crystal undergoes local distortions in basal planes of the initial hexagonal lattice. The local distortions are assumed to be sources of the formation of ferromagnetism in compounds of this class.

  17. Doping of two-dimensional MoS2 by high energy ion implantation

    NASA Astrophysics Data System (ADS)

    Xu, Kang; Zhao, Yuda; Lin, Ziyuan; Long, Yan; Wang, Yi; Chan, Mansun; Chai, Yang

    2017-12-01

    Two-dimensional (2D) materials have been demonstrated to be promising candidates for next generation electronic circuits. Analogues to conventional Si-based semiconductors, p- and n-doping of 2D materials are essential for building complementary circuits. Controllable and effective doping strategies require large tunability of the doping level and negligible structural damage to ultrathin 2D materials. In this work, we demonstrate a doping method utilizing a conventional high-energy ion-implantation machine. Before the implantation, a Polymethylmethacrylate (PMMA) protective layer is used to decelerate the dopant ions and minimize the structural damage to MoS2, thus aggregating the dopants inside MoS2 flakes. By optimizing the implantation energy and fluence, phosphorus dopants are incorporated into MoS2 flakes. Our Raman and high-resolution transmission electron microscopy (HRTEM) results show that only negligibly structural damage is introduced to the MoS2 lattice during the implantation. P-doping effect by the incorporation of p+ is demonstrated by Photoluminescence (PL) and electrical characterizations. Thin PMMA protection layer leads to large kinetic damage but also a more significant doping effect. Also, MoS2 with large thickness shows less kinetic damage. This doping method makes use of existing infrastructures in the semiconductor industry and can be extended to other 2D materials and dopant species as well.

  18. Preparation and characterization of Tb3+ ions doped zincborophosphate glasses for green emission

    NASA Astrophysics Data System (ADS)

    Bindu, S. Hima; Raju, D. Siva; Krishna, V. Vinay; Raju, Ch. Linga

    2017-06-01

    The present study reports the preparation of various concentrations of Tb3+ ions doped zincborophosphate glasses and analysis by XRD, FTIR, optical, emission and decay curve spectras. The effect of borate groups on the phosphate was evidenced by FTIR spectroscopy. The JO intensity parameters was calculated using Judd-Offlet theory. The fluroscence spectra of Tb3+ doped zincborophosphate glasses revealed the efficient blue and green emissions due to 5D3 and 5D4 excited levels to 7Fj ground state respectively. The decay curves exhibits single exponential curves for all the Tb3+ ion concentrations. Various radiative and fluorescence parameters are calculated using JO intensity parameters. Based on the results obtained in the present study, the Tb3+ ions doped zincborophosphate glasses behaves as a efficient laser active materials for highintensity emissions in the green region.

  19. Multiscale optical imaging of rare-earth-doped nanocomposites in a small animal model

    NASA Astrophysics Data System (ADS)

    Higgins, Laura M.; Ganapathy, Vidya; Kantamneni, Harini; Zhao, Xinyu; Sheng, Yang; Tan, Mei-Chee; Roth, Charles M.; Riman, Richard E.; Moghe, Prabhas V.; Pierce, Mark C.

    2018-03-01

    Rare-earth-doped nanocomposites have appealing optical properties for use as biomedical contrast agents, but few systems exist for imaging these materials. We describe the design and characterization of (i) a preclinical system for whole animal in vivo imaging and (ii) an integrated optical coherence tomography/confocal microscopy system for high-resolution imaging of ex vivo tissues. We demonstrate these systems by administering erbium-doped nanocomposites to a murine model of metastatic breast cancer. Short-wave infrared emissions were detected in vivo and in whole organ imaging ex vivo. Visible upconversion emissions and tissue autofluorescence were imaged in biopsy specimens, alongside optical coherence tomography imaging of tissue microstructure. We anticipate that this work will provide guidance for researchers seeking to image these nanomaterials across a wide range of biological models.

  20. Multiscale optical imaging of rare-earth-doped nanocomposites in a small animal model.

    PubMed

    Higgins, Laura M; Ganapathy, Vidya; Kantamneni, Harini; Zhao, Xinyu; Sheng, Yang; Tan, Mei-Chee; Roth, Charles M; Riman, Richard E; Moghe, Prabhas V; Pierce, Mark C

    2018-03-01

    Rare-earth-doped nanocomposites have appealing optical properties for use as biomedical contrast agents, but few systems exist for imaging these materials. We describe the design and characterization of (i) a preclinical system for whole animal in vivo imaging and (ii) an integrated optical coherence tomography/confocal microscopy system for high-resolution imaging of ex vivo tissues. We demonstrate these systems by administering erbium-doped nanocomposites to a murine model of metastatic breast cancer. Short-wave infrared emissions were detected in vivo and in whole organ imaging ex vivo. Visible upconversion emissions and tissue autofluorescence were imaged in biopsy specimens, alongside optical coherence tomography imaging of tissue microstructure. We anticipate that this work will provide guidance for researchers seeking to image these nanomaterials across a wide range of biological models. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

  1. Phase Transformation and Lattice Parameter Changes of Non-trivalent Rare Earth-Doped YSZ as a Function of Temperature

    NASA Astrophysics Data System (ADS)

    Jiang, Shengli; Huang, Xiao; He, Zhang; Buyers, Andrew

    2018-01-01

    To examine the effect of doping/co-doping on high-temperature phase compositions of YSZ, stand-alone YSZ and CeO2 and Nb2O5 co-doped YSZ samples were prepared using mechanical alloy and high-temperature sintering. XRD analysis was performed on these samples from room temperature to 1100 °C. The results show that the structure for the co-doped samples tends to be thermally stable when the test temperature is higher than a critical value. Monoclinic phase was dominant in Nb2O5 co-doped YSZ at temperatures lower than 600 °C, while for the YSZ and CeO2 co-doped YSZ, cubic/tetragonal phase was dominant in the whole test temperature range. The lattice parameters for all the samples increase with increasing test temperature generally. The lattice parameters for the two non-trivalent rare earth oxides co-doped YSZ show that the lattice parameter a for the cubic phase of the Ce4+ co-doped YSZ is consistently greater than that of 7YSZ which is related to the presence of larger radius of Ce4+ in the matrix. The lattice parameters a, b, c for the monoclinic phase of Ce4+ co-doped YSZ are much closer to each other than that of the Nb5+ co-doped YSZ, indicating the former has better tendency to form cubic/tetragonal phase, which is desired for vast engineering applications.

  2. Phase Transformation and Lattice Parameter Changes of Non-trivalent Rare Earth-Doped YSZ as a Function of Temperature

    NASA Astrophysics Data System (ADS)

    Jiang, Shengli; Huang, Xiao; He, Zhang; Buyers, Andrew

    2018-05-01

    To examine the effect of doping/co-doping on high-temperature phase compositions of YSZ, stand-alone YSZ and CeO2 and Nb2O5 co-doped YSZ samples were prepared using mechanical alloy and high-temperature sintering. XRD analysis was performed on these samples from room temperature to 1100 °C. The results show that the structure for the co-doped samples tends to be thermally stable when the test temperature is higher than a critical value. Monoclinic phase was dominant in Nb2O5 co-doped YSZ at temperatures lower than 600 °C, while for the YSZ and CeO2 co-doped YSZ, cubic/tetragonal phase was dominant in the whole test temperature range. The lattice parameters for all the samples increase with increasing test temperature generally. The lattice parameters for the two non-trivalent rare earth oxides co-doped YSZ show that the lattice parameter a for the cubic phase of the Ce4+ co-doped YSZ is consistently greater than that of 7YSZ which is related to the presence of larger radius of Ce4+ in the matrix. The lattice parameters a, b, c for the monoclinic phase of Ce4+ co-doped YSZ are much closer to each other than that of the Nb5+ co-doped YSZ, indicating the former has better tendency to form cubic/tetragonal phase, which is desired for vast engineering applications.

  3. All-optical control of long-lived nuclear spins in rare-earth doped nanoparticles.

    PubMed

    Serrano, D; Karlsson, J; Fossati, A; Ferrier, A; Goldner, P

    2018-05-29

    Nanoscale systems that coherently couple to light and possess spins offer key capabilities for quantum technologies. However, an outstanding challenge is to preserve properties, and especially optical and spin coherence lifetimes, at the nanoscale. Here, we report optically controlled nuclear spins with long coherence lifetimes (T 2 ) in rare-earth-doped nanoparticles. We detect spins echoes and measure a spin coherence lifetime of 2.9 ± 0.3 ms at 5 K under an external magnetic field of 9 mT, a T 2 value comparable to those obtained in bulk rare-earth crystals. Moreover, we achieve spin T 2 extension using all-optical spin dynamical decoupling and observe high fidelity between excitation and echo phases. Rare-earth-doped nanoparticles are thus the only nano-material in which optically controlled spins with millisecond coherence lifetimes have been reported. These results open the way to providing quantum light-atom-spin interfaces with long storage time within hybrid architectures.

  4. Rare-earth-doped optical-fiber core deposition using full vapor-phase SPCVD process

    NASA Astrophysics Data System (ADS)

    Barnini, A.; Robin, T.; Cadier, B.; Aka, G.; Caurant, D.; Gotter, T.; Guyon, C.; Pinsard, E.; Guitton, P.; Laurent, A.; Montron, R.

    2017-02-01

    One key parameter in the race toward ever-higher power fiber lasers remains the rare earth doped optical core quality. Modern Large Mode Area (LMA) fibers require a fine radial control of the core refractive index (RI) close to the silica level. These low RI are achieved with multi-component materials that cannot be readily obtained using conventional solution doping based Modified Chemical Vapor Deposition (MCVD) technology. This paper presents a study of such optical material obtained through a full-vapor phase Surface Plasma Chemical Vapor Deposition (SPCVD). The SPCVD process generates straight glassy films on the inner surface of a thermally regulated synthetic silica tube under vacuum. The first part of the presented results points out the feasibility of ytterbium-doped aluminosilicate fibers by this process. In the second part we describe the challenge controlling the refractive index throughout the core diameter when using volatile fluorine to create efficient LMA fiber profiles. It has been demonstrated that it is possible to counter-act the loss of fluorine at the center of the core by adjusting the core composition locally. Our materials yielded, when used in optical fibers with numerical apertures ranging from 0.07 to 0.09, power conversion efficiency up to 76% and low background losses below 20 dB/km at 1100nm. Photodarkening has been measured to be similar to equivalent MCVD based fibers. The use of cerium as a co-dopant allowed for a complete mitigation of this laser lifetime detrimental effect. The SPCVD process enables high capacity preforms and is particularly versatile when it comes to radial tailoring of both rare earth doping level and RI. Large core diameter preforms - up to 4mm - were successfully produced.

  5. Effect of particle size and dopant concentration on photophysical properties of Eu3+-doped rare earth oxysulphide phosphor coatings.

    PubMed

    Chakradhar, R P S; Basu, Bharathibai J; Lakshmi, R V

    2011-02-01

    Europium-doped rare-earth oxysulphides (red phosphors) are often used as reference luminophore in pyrene-based pressure sensor coatings for aerodynamic applications. Different red phosphor samples were characterized for their particle size, chemical composition, photoluminescent properties and temperature sensitivity. The red phosphor samples were characterized using energy-dispersive X-ray spectroscopy (EDX) for elemental analysis and scanning electron microscopy (SEM) for morphology and particle size measurement. The particle size was in the range of 1.5-5.7 μm with morphology of hexagonal or spherical shape. It was found that phosphor with higher europium content exhibited higher luminescent emission intensity. The phosphor coatings were prepared by spraying a dispersion of the material in silicone resin. Smooth coatings were obtained by using phosphor samples with smaller particle size. Upon 334 nm excitation, the coatings showed characteristic luminescence 5D0→7FJ (J=0, 1, 2, 3, 4) of the Eu3+ ions. The electronic transition located at 626 nm (5D0→7F2) of Eu3+ ions was stronger than the magnetic dipole transition located at 595 nm (5D0→7F1). Luminescence decay curves obeyed double exponential behaviour. The phosphor samples showed temperature sensitivity of -0.012 to -0.168%/°C in the temperature range of 25-50 °C. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. Health Sensing Functions in Thermal Barrier Coatings Incorporating Rare-Earth-Doped Luminescent Sublayers

    NASA Technical Reports Server (NTRS)

    Eldridge, J. I.; Singh, J.; Wolfe, D. E.

    2004-01-01

    Great effort has been directed towards developing techniques to monitor the health of thermal barrier coatings (TBCs) that would detect the approach of safety-threatening conditions. An unconventional approach is presented here where health sensing functionality is integrated into the TBC itself by the incorporation of rare-earth-doped luminescent sublayers to monitor erosion as well as whether the TBC is maintaining the underlying substrate at a sufficiently low temperature. Erosion indication is demonstrated in electron-beam physical vapor deposited (EB-PVD) TBCs consisting of 7wt% yttria-stabilized zirconia (7YSZ) with europium-doped and terbium-doped sublayers. Multiple ingot deposition produced sharp boundaries between the doped sublayers without interrupting the columnar growth of the TBC. The TBC-coated specimens were subjected to alumina particle jet erosion, and the erosion depth was then indicated under ultraviolet illumination that excited easily visible luminescence characteristic of sublayer that was exposed by erosion. In addition, temperature measurements from a bottom-lying europium-doped sublayer in a TBC produced by multiple ingot EB-PVD were accomplished by measuring the temperature-dependent decay time from the 606 nm wavelength emission excited in that sublayer with a 532 nm wavelength laser that was selected for its close match to one of the europium excitation wavelengths as well as being at a wavelength where the TBC is relatively transparent. It is proposed the low dopant levels and absence of interruption of the TBC columnar growth allow the addition of the erosion and temperature sensing functions with minimal effects on TBC performance.

  7. Synthesis, characterization and luminescent properties of mixed phase bismuth molybdate-doped with Eu3+ ions

    NASA Astrophysics Data System (ADS)

    Wang, Liyong; Guo, Xiaoqing; Cai, Xiaomeng; Song, Qingwei; Han, Yuanyuan; Jia, Guang

    2018-02-01

    Red phosphors of Eu3+-doped bismuth molybdate (BMO) are prepared by a low temperature hydrothermal method assisting with Phenol Formaldehyde resin (PFr), and characterized by X-ray diffraction (XRD) patterns, Fourier transform infrared-spectroscopy (FT-IR), thermogravimetric analyzer (TGA), differential thermal analyzer (DTA), and photoluminescence (PL) spectroscopy. PL properties influence factors including molar ratio of Bi3+ and Mo3+ ions, PFr dosage and dopants concentration are discussed in detail. The results show that BMO can act as a useful host for Eu3+ ions doping, and energy transferring from Bi3+ to Eu3+ achieved efficiently, the BMO phosphors displayed intense red color emission under ultraviolet light excitation.

  8. Superposition-model analysis of rare-earth doped BaY2F8

    NASA Astrophysics Data System (ADS)

    Magnani, N.; Amoretti, G.; Baraldi, A.; Capelletti, R.

    The energy level schemes of four rare-earth dopants (Ce3+ , Nd3+ , Dy3+ , and Er3+) in BaY2 F-8 , as determined by optical absorption spectra, were fitted with a single-ion Hamiltonian and analysed within Newman's Superposition Model for the crystal field. A unified picture for the four dopants was obtained, by assuming a distortion of the F- ligand cage around the RE site; within the framework of the Superposition Model, this distortion is found to have a marked anisotropic behaviour for heavy rare earths, while it turns into an isotropic expansion of the nearest-neighbours polyhedron for light rare earths. It is also inferred that the substituting ion may occupy an off-center position with respect to the original Y3+ site in the crystal.

  9. Mechanism of Na-Ion Storage in Hard Carbon Anodes Revealed by Heteroatom Doping

    SciT

    Li, Zhifei; Bommier, Clement; Chong, Zhi Sen

    Hard carbon is the candidate anode material for the commercialization of Na-ion batteries the batteries that by virtue of being constructed from inexpensive and abundant components open the door for massive scale up of battery-based storage of electrical energy. Holding back the development of these batteries is that a complete understanding of the mechanism of Na-ion storage in hard carbon has remained elusive. Although as an amorphous carbon, hard carbon possesses a subtle and complex structure composed of domains of layered rumpled sheets that have local order resembling graphene within each layer but complete disorder along the c-axis between layers.more » Here, we present two key discoveries: first that characteristics of hard carbon s structure can be modified systematically by heteroatom doping, and second, that these changes greatly affect Na-ion storage properties, which reveal the mechanisms for Na storage in hard carbon. Specifically, P, S and B doping was used to engineer the density of local defects in graphenic layers, and to modify the spacing between the layers. While opening the interlayer spacing through P or S doping extends the low-voltage capacity plateau, and increasing the defect concentration with P or B doping high first sodiation capacity is achieved. Furthermore, we observe that the highly defective B-doped hard carbon suffers a tremendous irreversible capacity in the first desodiation cycle. Our combined first principles calculations and experimental studies revealed a new trapping mechanism, showing that the high binding energies between B-doping induced defects and Na-ions are responsible for the irreversible capacity. The understanding generated in this work provides a totally new set of guiding principles for materials engineers working to optimize hard carbon for Na-ion battery applications.« less

  10. Mechanism of Na-Ion Storage in Hard Carbon Anodes Revealed by Heteroatom Doping

    DOE PAGES

    Li, Zhifei; Bommier, Clement; Chong, Zhi Sen; ...

    2017-05-23

    Hard carbon is the candidate anode material for the commercialization of Na-ion batteries the batteries that by virtue of being constructed from inexpensive and abundant components open the door for massive scale up of battery-based storage of electrical energy. Holding back the development of these batteries is that a complete understanding of the mechanism of Na-ion storage in hard carbon has remained elusive. Although as an amorphous carbon, hard carbon possesses a subtle and complex structure composed of domains of layered rumpled sheets that have local order resembling graphene within each layer but complete disorder along the c-axis between layers.more » Here, we present two key discoveries: first that characteristics of hard carbon s structure can be modified systematically by heteroatom doping, and second, that these changes greatly affect Na-ion storage properties, which reveal the mechanisms for Na storage in hard carbon. Specifically, P, S and B doping was used to engineer the density of local defects in graphenic layers, and to modify the spacing between the layers. While opening the interlayer spacing through P or S doping extends the low-voltage capacity plateau, and increasing the defect concentration with P or B doping high first sodiation capacity is achieved. Furthermore, we observe that the highly defective B-doped hard carbon suffers a tremendous irreversible capacity in the first desodiation cycle. Our combined first principles calculations and experimental studies revealed a new trapping mechanism, showing that the high binding energies between B-doping induced defects and Na-ions are responsible for the irreversible capacity. The understanding generated in this work provides a totally new set of guiding principles for materials engineers working to optimize hard carbon for Na-ion battery applications.« less

  11. Effects of rare-earth co-doping on the local structure of rare-earth phosphate glasses using high and low energy X-ray diffraction.

    PubMed

    Cramer, Alisha J; Cole, Jacqueline M; FitzGerald, Vicky; Honkimaki, Veijo; Roberts, Mark A; Brennan, Tessa; Martin, Richard A; Saunders, George A; Newport, Robert J

    2013-06-14

    Rare-earth co-doping in inorganic materials has a long-held tradition of facilitating highly desirable optoelectronic properties for their application to the laser industry. This study concentrates specifically on rare-earth phosphate glasses, (R2O3)x(R'2O3)y(P2O5)(1-(x+y)), where (R, R') denotes (Ce, Er) or (La, Nd) co-doping and the total rare-earth composition corresponds to a range between metaphosphate, RP3O9, and ultraphosphate, RP5O14. Thereupon, the effects of rare-earth co-doping on the local structure are assessed at the atomic level. Pair-distribution function analysis of high-energy X-ray diffraction data (Q(max) = 28 Å(-1)) is employed to make this assessment. Results reveal a stark structural invariance to rare-earth co-doping which bears testament to the open-framework and rigid nature of these glasses. A range of desirable attributes of these glasses unfold from this finding; in particular, a structural simplicity that will enable facile molecular engineering of rare-earth phosphate glasses with 'dial-up' lasing properties. When considered together with other factors, this finding also demonstrates additional prospects for these co-doped rare-earth phosphate glasses in nuclear waste storage applications. This study also reveals, for the first time, the ability to distinguish between P-O and P[double bond, length as m-dash]O bonding in these rare-earth phosphate glasses from X-ray diffraction data in a fully quantitative manner. Complementary analysis of high-energy X-ray diffraction data on single rare-earth phosphate glasses of similar rare-earth composition to the co-doped materials is also presented in this context. In a technical sense, all high-energy X-ray diffraction data on these glasses are compared with analogous low-energy diffraction data; their salient differences reveal distinct advantages of high-energy X-ray diffraction data for the study of amorphous materials.

  12. Alkaline earth metal and samarium co-doped ceria as efficient electrolytes

    NASA Astrophysics Data System (ADS)

    Ali, Amjad; Raza, Rizwan; Kaleem Ullah, M.; Rafique, Asia; Wang, Baoyuan; Zhu, Bin

    2018-01-01

    Co-doped ceramic electrolytes M0.1Sm0.1Ce0.8O2-δ (M = Ba, Ca, Mg, and Sr) were synthesized via co-precipitation. The focus of this study was to highlight the effects of alkaline earth metals in doped ceria on the microstructure, densification, conductivity, and performance. The ionic conductivity comparisons of prepared electrolytes in the air atmosphere were studied. It has been observed that Ca0.1Sm0.1Ce0.8O2-δ shows the highest conductivity of 0.124 Scm-1 at 650 °C and a lower activation energy of 0.48 eV. The cell shows a maximum power density of 630 mW cm-2 at 650 °C using hydrogen fuel. The enhancement in conductivity and performance was due to increasing the oxygen vacancies in the ceria lattice with the increasing dopant concentration. The bandgap was calculated from UV-Vis data, which shows a red shift when compared with pure ceria. The average crystallite size is in the range of 37-49 nm. DFT was used to analyze the co-doping structure, and the calculated lattice parameter was compared with the experimental lattice parameter.

  13. Specific features of doping with antimony during the ion-beam crystallization of silicon

    SciT

    Pashchenko, A. S., E-mail: as.pashchenko@gmail.com; Chebotarev, S. N.; Lunin, L. S.

    2016-04-15

    A method of doping during the growth of thin films by ion-beam crystallization is proposed. By the example of Si and Sb, the possibility of controllably doping semiconductors during the ion-beam crystallization process is shown. A calibrated temperature dependence of the antimony vapor flow rate in the range from 150 to 400°C is obtained. It is established that, an increase in the evaporator temperature above 200°C brings about the accumulation of impurities in the layer growth direction. Silicon layers doped with antimony to a concentration of 10{sup 18} cm{sup –3} are grown. It is shown that, as the evaporator temperaturemore » is increased, the efficiency of the activation of antimony in silicon nonlinearly decreases from ~10{sup 0} to ~10{sup –3}.« less

  14. Rare earth doped III-nitride semiconductors for spintronic and optoelectronic applications (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Palai, Ratnakar

    2016-10-01

    Since last four decades the information and communication technologies are relying on the semiconductor materials. Currently a great deal of attention is being focused on adding spin degree-of-freedom into semiconductor to create a new area of solid-state electronics, called spintronics. In spintronics not only the current but also its spin state is controlled. Such materials need to be good semiconductors for easy integration in typical integrated circuits with high sensitivity to the spin orientation, especially room temperature ferromagnetism being an important desirable property. GaN is considered to be the most important semiconductor after silicon. It is widely used for the production of green, blue, UV, and white LEDs in full color displays, traffic lights, automotive lightings, and general room lighting using white LEDs. GaN-based systems also show promise for microwave and high power electronics intended for radar, satellite, wireless base stations and spintronic applications. Rare earth (Yb, Eu, Er, and Tm) doped GaN shows many interesting optoelectronic and magnetoptic properties e. g. sharp emission from UV through visible to IR, radiation hardness, and ferromagnetism. The talk will be focused on fabrication, optoelectronic (photoluminescence, cathodeluminescence, magnetic, and x-ray photoelectron spectroscopy) properties of some rare earth doped GaN and InGaN semiconductor nanostructures grown by plasma assisted molecular beam epitaxy (MBE) and future applications.

  15. The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films.

    PubMed

    Gudjonsdottir, Solrun; van der Stam, Ward; Kirkwood, Nicholas; Evers, Wiel H; Houtepen, Arjan J

    2018-05-16

    Control over the charge density is very important for implementation of colloidal semiconductor nanocrystals into various optoelectronic applications. A promising approach to dope nanocrystal assemblies is charge injection by electrochemistry, in which the charge compensating electrolyte ions can be regarded as external dopant ions. To gain insight into the doping mechanism and the role of the external dopant ions, we investigate charge injection in ZnO nanocrystal assemblies for a large series of charge compensating electrolyte ions with spectroelectrochemical and electrochemical transistor measurements. We show that charge injection is limited by the diffusion of cations in the nanocrystal films as their diffusion coefficient are found to be ∼7 orders of magnitude lower than those of electrons. We further show that the rate of charge injection depends strongly on the cation size and cation concentration. Strikingly, the onset of electron injection varies up to 0.4 V, depending on the size of the electrolyte cation. For the small ions Li + and Na + the onset is at significantly less negative potentials. For larger ions (K + , quaternary ammonium ions) the onset is always at the same, more negative potential, suggesting that intercalation may take place for Li + and Na + . Finally, we show that the nature of the charge compensating cation does not affect the source-drain electronic conductivity and mobility, indicating that shallow donor levels from intercalating ions fully hybridize with the quantum confined energy levels and that the reorganization energy due to intercalating ions does not strongly affect electron transport in these nanocrystal assemblies.

  16. Tunable dielectric response and electronic conductivity of potassium-ion-doped tunnel-structured manganese oxides

    NASA Astrophysics Data System (ADS)

    He, Gaihua; Duan, Yuping; Song, Lulu; Zhang, Xuefeng

    2018-06-01

    Potassium-ion-doped MnO2 has been successfully synthesized using the hydrothermal method, and the influence of the doped potassium ions on the electrical conductivity and permittivity is studied. X-ray powder diffraction, scanning electron microscopy, electron-probe micro-analysis, and a vector network analyzer are used to perform characterization. The densities of states of doped and undoped MnO2 tunnel structures are also discussed based on first-principles calculations. Results show that the conductivity and dielectric resonance of MnO2 can be elevated by means of K+ doping. The conductivity of K+-doped MnO2 prepared at different reaction times shows a decreasing trend and is generally 1 order of magnitude higher than that of pure MnO2. The electrical conductivity of K+-doped MnO2 (R3) shows the highest value of 3.33 × 10-2 S/cm at the reaction time of 24 h, while that of pure MnO2 is 8.50 × 10-4 S/cm. When treated with acid, the conductivity of samples remains basically stable along with the increase of treatment time. In addition, acid treatment plays a very significant role in controlling the amount of K+ ions in crystals. The K+ contents of acid-treated samples are 5 times lower than that of the untreated R1. The dielectric losses of the samples with different reaction times are enhanced markedly with frequency increment. The complex permittivity of pure MnO2 only exhibits a resonance at ˜12 GHz, while K+-doped MnO2 exhibits another resonance behavior at ˜9 GHz. The capacity of the dielectric property in the net structure is enhanced by the interfacial polarization, dielectric relaxation, multiple internal reflections, and multiple scattering benefiting.

  17. Rare-earth metal oxide doped transparent mesoporous silica plates under non-aqueous condition as a potential UV sensor.

    PubMed

    Lee, Sang-Joon; Park, Sung Soo; Lee, Sang Hyun; Hong, Sang-Hyun; Ha, Chang-Sik

    2013-11-01

    Transparent mesoporous silica plates doped with rare-earth metal oxide were prepared using solvent-evaporation method based on the self-organization between structure-directing agent and silicate in a non-aqueous solvent. A triblock copolymer, Pluronic (F127 or P123), was used as the structure-directing agent, while tetraethyl orthosilicate (TEOS) was used as a silica source. The pore diameter and the surface area of the mesoporous silica plate prepared with the optimized conditions were ca 40 A and 600 m2 g(-1), respectively, for both structure-directing agent. Rare-earth metal oxides (Eu, Tb, Tm oxide) in mesochannel were formed via one-step synthetic route based on the preparation method of a silica plate. Optical properties of rare-earth metal oxide-doped mesoporous silica plates were investigated by UV irradiation and photoluminescence (PL) spectroscopy. Under the exitation wavelength of 254 nm, the doped mesoporous silica plates emitted red, green and blue for Eu, Tb and Tm oxides, respectively. Rare-earth metal oxide-doped mesoporous silica plates showed enhanced PL intensity compared to that of the bulk rare-earth metal oxide.

  18. Changes in optical spectra of silver nanoparticles doped europium ions

    NASA Astrophysics Data System (ADS)

    Rasmagin, S. I.; Krasovskii, V. I.; Novikov, I. K.; Kryshtob, V. I.; Kazaryan, M. A.

    2018-04-01

    Colloidal solutions of Ag silver nanoparticles were studied in the presence of Eu3+ ions and in the absence of their. Silver nanoparticles were created by the method of green synthesis using an aqueous solution of mint. Optical and electronic spectroscopy have been used to explore the interaction of these ions with silver nanoparticles.

  19. Towards a new class of heavy ion doped magnetic semiconductors for room temperature applications

    PubMed Central

    Lee, Juwon; Subramaniam, Nagarajan Ganapathi; Agnieszka Kowalik, Iwona; Nisar, Jawad; Lee, Jaechul; Kwon, Younghae; Lee, Jaechoon; Kang, Taewon; Peng, Xiangyang; Arvanitis, Dimitri; Ahuja, Rajeev

    2015-01-01

    The article presents, using Bi doped ZnO, an example of a heavy ion doped oxide semiconductor, highlighting a novel p-symmetry interaction of the electronic states to stabilize ferromagnetism. The study includes both ab initio theory and experiments, which yield clear evidence for above room temperature ferromagnetism. ZnBixO1−x thin films are grown using the pulsed laser deposition technique. The room temperature ferromagnetism finds its origin in the holes introduced by the Bi doping and the p-p coupling between Bi and the host atoms. A sizeable magnetic moment is measured by means of x-ray magnetic circular dichroism at the O K-edge, probing directly the spin polarization of the O(2p) states. This result is in agreement with the theoretical predictions and inductive magnetometry measurements. Ab initio calculations of the electronic and magnetic structure of ZnBixO1−x at various doping levels allow to trace the origin of the ferromagnetic character of this material. It appears, that the spin-orbit energy of the heavy ion Bi stabilizes the ferromagnetic phase. Thus, ZnBixO1−x doped with a heavy non-ferromagnetic element, such as Bi, is a credible example of a candidate material for a new class of compounds for spintronics applications, based on the spin polarization of the p states. PMID:26592564

  20. Optical studies of Sm³⁺ ions doped zinc alumino bismuth borate glasses.

    PubMed

    Swapna, K; Mahamuda, Sk; Srinivasa Rao, A; Shakya, S; Sasikala, T; Haranath, D; Vijaya Prakash, G

    2014-05-05

    Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of samarium (Sm(3+)) ions were prepared by using melt quenching technique and characterized for their lasing potentialities in visible region by using the techniques such as optical absorption, emission and emission decay measurements. Radiative properties for various fluorescent levels of Sm(3+) ions were estimated from absorption spectral information using Judd-Ofelt (JO) analysis. The emission spectra and con-focal photoluminescence images obtained by 410 nm laser excitation demonstrates very distinct and intense orange-red emission for all the doped glasses. The suitable concentration of Sm(3+) ions in these glasses to act as an efficient lasing material has been discussed by measuring the emission cross-section and branching ratios for the emission transitions. The quantum efficiencies were also been estimated from emission decay measurements recorded for the (4)G5/2 level of Sm(3+) ions. From the measured emission cross-sections, branching ratios, strong photoluminescence features and CIE chromaticity coordinates, it was found that 1 mol% of Sm(3+) ions doped ZnAlBiB glasses are most suitable for the development of visible orange-red lasers. Copyright © 2014 Elsevier B.V. All rights reserved.

  1. Fluorine-doped antiperovskite electrolyte for all-solid-state Lithium-ion batteries

    DOE PAGES

    Li, Yutao; Zhou, Weidong; Xin, Sen; ...

    2016-06-30

    A fluorine-doped antiperovskite Li-ion conducto Li 2(OH)X (X=Cl, Br) is shown to be a promising candidat for a solid electrolyte in an all-solid-state Li-ion rechargeabl battery. Substitution of F¯ for OH¯ transforms orthorhombi Li 2OHCl to a room-temperature cubic phase, which show electrochemical stability to 9 V versus Li +/Li and two orders o magnitude higher Li-ion conductivity than that of orthorhombi Li 2OHCl. As a result, an all-solid-state Li/LiFePO 4 with F-dope Li 2OHCl as the solid electrolyte showed good cyclability an a high coulombic efficiency over 40 charge/discharge cycles

  2. Ion transport mechanisms in lamellar phases of salt-doped PS-PEO block copolymer electrolytes.

    PubMed

    Sethuraman, Vaidyanathan; Mogurampelly, Santosh; Ganesan, Venkat

    2017-11-01

    We use a multiscale simulation strategy to elucidate, at an atomistic level, the mechanisms underlying ion transport in the lamellar phase of polystyrene-polyethylene oxide (PS-PEO) block copolymer (BCP) electrolytes doped with LiPF 6 salts. Explicitly, we compare the results obtained for ion transport in the microphase separated block copolymer melts to those for salt-doped PEO homopolymer melts. In addition, we also present results for dynamics of the ions individually in the PEO and PS domains of the BCP melt, and locally as a function of the distance from the lamellar interfaces. When compared to the PEO homopolymer melt, ions were found to exhibit slower dynamics in both the block copolymer (overall) and in the PEO phase of the BCP melt. Such results are shown to arise from the effects of slower polymer segmental dynamics in the BCP melt and the coordination characteristics of the ions. Polymer backbone-ion residence times analyzed as a function of distance from the interface indicate that ions have a larger residence time near the interface compared to that near the bulk of lamella, and demonstrates the influence of the glassy PS blocks and microphase segregation on the ion transport properties. Ion transport mechanisms in BCP melts reveal that there exist five distinct mechanisms for ion transport along the backbone of the chain and exhibit qualitative differences from the behavior in homopolymer melts. We also present results as a function of salt concentration which show that the mean-squared displacements of the ions decrease with increasing salt concentration, and that the ion residence times near the polymer backbone increase with increasing salt concentration.

  3. On the role of Fe ions on magnetic properties of doped TiO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Tolea, F.; Grecu, M. N.; Kuncser, V.; Constantinescu, S. Gr.; Ghica, D.

    2015-04-01

    The role of iron doping on magnetic properties of hydrothermal anatase TiO2:57Fe (0-1 at. %) nanoparticles is investigated by combining superconducting quantum interference device magnetometry with Mössbauer and electron paramagnetic resonance techniques. The results on both as-prepared and thermally treated samples in reduced air atmosphere reveal complexity of magnetic interactions, in connection to certain iron ion electron configurations and defects (oxygen vacancies, F-center, and Ti3+ ions). The distribution of iron ions is predominantly at nanoparticle surface layers. Formation of weak ferromagnetic domains up to 380 K is mainly related to defects, supporting the bound magnetic polaron model.

  4. Conductivity studies of Chitosan doped with different ammonium salts: Effect of ion size

    NASA Astrophysics Data System (ADS)

    Mohan, C. Raja; Senthilkumar, M.; Jayakumar, K.

    2015-06-01

    In the present investigation influence of ion size on the electrical properties of various ammonium salts of various concentrations doped with Chitosan liquid electrolyte has been studied. The attachment of ammonium salts with Chitosan has been confirmed through FTIR Spectrum. Polarizability is calculated from the refractive index data. Addition of ammonium salts increases the conductivity. It is also observed that increase in ion size, increases the ionic conductivity due to increase in amorphous nature of the material. Increase in concentration leads to increase in conductivity due to the presence of more number of free ions.

  5. Barcoded materials based on photoluminescent hybrid system of lanthanide ions-doped metal organic framework and silica via ion exchange.

    PubMed

    Shen, Xiang; Yan, Bing

    2016-04-15

    A multicolored photoluminescent hybrid system based on lanthanide ions-doped metal organic frameworks/silica composite host has potential in display and barcode applications. By controlling the stoichiometry of the lanthanides via cation exchange, proportional various lanthanide ions are successfully introduced into metal organic frameworks, whose emission intensity is correspondingly proportional to its amount. The resulting luminescent barcodes depend on the lanthanide ions ratios and compositions. Subsequently, the lanthanide ions located in the channels of metal organic frameworks are protected from any interaction with the environment after the modification of silica on the surface. The optical and thermal stability of the hybrid materials are improved for technological application. Copyright © 2016 Elsevier Inc. All rights reserved.

  6. Comparative thermometric properties of bi-functional Er3+-Yb3+ doped rare earth (RE = Y, Gd and La) molybdates

    NASA Astrophysics Data System (ADS)

    Sinha, Shriya; Mahata, Manoj Kumar; Kumar, Kaushal

    2018-02-01

    The molybdate compounds as luminescent medium have received great attention of recent research due to their excellent intrinsic optical properties. Therefore, the investigation on the optical thermometry and nanoheating effect in Er3+-Yb3+ doped molybdates of yttrium (EYYMO), gadolinium (EYGMO) and lanthanum (EYLMO) nanophosphors is reported herein. The temperature dependent fluorescence intensity ratio of green (525 and 548 nm) emission bands of Er3+ ions were analyzed within 300-500 K temperature range to determine the thermal behavior. The comparative temperature sensitivity of the materials has been found to depend on the phonon energy of their own. The thermal sensitivity is higher in the materials with low phonon energy. The intensity ratio of the green emission bands has been found to alter with the laser excitation density, which can be used to estimate the induced temperature in the materials. Furthermore, the photothermal conversion efficiency is calculated in the water dispersed samples and the maximum photothermal conversion efficiency of 49.6% is achieved for EYGMO nanophosphor. Comparative experimental results explore unequal thermal sensing and induced optical heating in the three rare earth molybdates. The optical properties of the green emitting molybdates are interesting for temperature sensing and optical heating applications.

  7. Atomic-Level Structure Studies of Rare-Earth Doped Sodium Phosphate Glasses Using High Energy X-Ray Diffraction and Complementary Techniques

    NASA Astrophysics Data System (ADS)

    Amir, Faisal

    The atomic-scale structure of a series of (RE2 O3)x ( Na2O)y ( P2O5)1- x-y glasses (RE = Pr, Nd, Er) where has been characterized by high-energy X-ray diffraction technique (HEXRD). In addition, differential thermal analysis (DTA), Fourier transform infrared (FTIR) spectroscopy, and absorption and emission spectroscopy in visible and near IR ranges have been used as supplementary tools to validate structural features obtained from HEXRD techniques.Structural features such as inter-atomic distances and coordination numbers and their dependence on the concentration of RE 2 O3 have been obtained by analyzing pair distribution functions (PDF) extracted from diffraction data. Coordination numbers for P-O, Na-O, O-O, and P-P were found to be independent of the RE 2 O3 concentration. In contrast, the RE-O coordination number varies between ≈ 8 and 7.2 as the RE2 O3 concentration increases from 0.005 to 0.05. The variation of the bond distance between large rare-earth ions (Pr, Nd) and small rare-earth ion (Er) is approximately 0.2 A, which is attributed to lanthanide contraction. The Na-O coordination number in these glasses was observed to ≈ 5.0 as the RE2 O 3 content increases. The overlapping correlation of RE-O, Na-O, and O-O in the same vicinity makes it difficult to calculate these coordination numbers. DTA measurements were used for the investigation of thermal characteristics of glasses. From these measurements, it is evident that the glass transition temperature increases with increasing the RE2 O3 (RE=Pr, Er) content. FTIR was used to inspect the structural changes of the glasses. The doping of RE 2 O3 (RE=Pr, Er) induces depolymerization of the glasses at the Q3 tetrahedral sites. The forming of the ionic linkages between phosphate chains is attributed to the increase in non-bridging oxygen (NBO). The cross-linkages density (CLD) increases with the RE2 O3 (RE=Pr, Er) concentrations. Absorption spectra for x = 0.01 of Er 3+ and 0.005-0.05 for Nd3+ doped

  8. Rare earth-doped lead borate glasses and transparent glass-ceramics: structure-property relationship.

    PubMed

    Pisarski, W A; Pisarska, J; Mączka, M; Lisiecki, R; Grobelny, Ł; Goryczka, T; Dominiak-Dzik, G; Ryba-Romanowski, W

    2011-08-15

    Correlation between structure and optical properties of rare earth ions in lead borate glasses and glass-ceramics was evidenced by X-ray-diffraction, Raman, FT-IR and luminescence spectroscopy. The rare earths were limited to Eu(3+) and Er(3+) ions. The observed BO(3)↔BO(4) conversion strongly depends on the relative PbO/B(2)O(3) ratios in glass composition, giving important contribution to the luminescence intensities associated to (5)D(0)-(7)F(2) and (5)D(0)-(7)F(1) transitions of Eu(3+). The near-infrared luminescence and up-conversion spectra for Er(3+) ions in lead borate glasses before and after heat treatment were measured. The more intense and narrowing luminescence lines suggest partial incorporation of Er(3+) ions into the orthorhombic PbF(2) crystalline phase, which was identified using X-ray diffraction analysis. Copyright © 2010 Elsevier B.V. All rights reserved.

  9. Structure and size of ions electrochemically doped in conducting polymer

    NASA Astrophysics Data System (ADS)

    Kaneto, Keiichi; Hata, Fumito; Uto, Sadahito

    2018-05-01

    Among electroactive polymers (EAPs) for softactuators, conducting polymers have been intensively studied because of the large strain and stress caused by a low voltage operation. A larger deformation is desirable to extend their cycle life by reducing the operation voltage, and this is advantageous for their potential use in wider applications. The deformation is generated by the insertion of ions by electrochemical oxidation; hence, the magnitude of the strain depends on the bulkiness of the ions in the electrolytes. It is important, therefore, to clarify the structure and size of the ions during the electrochemical cycle, in order to achieve better performance of actuation. Anion and cation sizes (radii) in polypyrrole (PPy) film have been estimated using the precise measurement of strain against the amount of charge injected during the electrochemical cycles, assuming isotropic deformation of the film. The anion size was estimated using an anion-drive film, which was electrodeposited in TBABF4/methyl benzoate. The film was electrochemically cycled in sodium electrolytes, and the strain was measured simultaneously using a laser displacement meter. The cation size was obtained using a cation-drive film, being electropolymerized in aqueous dodecylbenzene sulfonic (DBS) acid. The cation-drive film was cycled in chloride electrolytes and measured the strain. The Cl-, Br-, NO3- , BF4- , and ClO4- radii were found to be approximately 235, 245, 250, 270 and 290 pm, respectively. The radii of K+, Na+ and Li+ were approximately 230, 237 and 274 pm, respectively. The results were discussed and took the crystalline ion radius and hydrated ion radius (Stokes radius) into consideration. It was found that the structure and size of the anions were slightly larger than the crystalline ion radius. Contrary to the anions, the cation radii were close to the hydrated ion radius, being larger than the crystalline ion radius.

  10. Near equality of ion phase space densities at earth, Jupiter, and Saturn

    NASA Technical Reports Server (NTRS)

    Cheng, A. F.; Krimigis, S. M.; Armstrong, T. P.

    1985-01-01

    Energetic-ion phase-space density profiles are strikingly similar in the inner magnetospheres of earth, Jupiter, and Saturn for ions of first adiabatic invariant near 100 MeV/G and small mirror latitudes. Losses occur inside L approximately equal to 7 for Jupiter and Saturn and inside L approximately equal to 5 at earth. At these L values there exist steep plasma-density gradients at all three planets, associated with the Io plasma torus at Jupiter, the Rhea-Dione-Tethys torus at Saturn, and the plasmasphere at earth. Measurements of ion flux-tube contents at Jupiter and Saturn by the low-energy charged-particle experiment show that these are similar (for O ions at L = 5-9) to those at earth (for protons at L = 2-6). Furthermore, the thermal-ion flux-tube contents from Voyager plasma-science data at Jupiter and Saturn are also very nearly equal, and again similar to those at earth, differing by less than a factor of 3 at the respective L values. The near equality of energetic and thermal ion flux-tube contents at earth, Jupiter, and Saturn suggests the possibility of strong physical analogies in the interaction between plasma and energetic particles at the plasma tori/plasma sheets of Jupiter and Saturn and the plasmasphere of earth.

  11. The heavy ion diffusion region in magnetic reconnection in the Earth's magnetotail

    NASA Astrophysics Data System (ADS)

    Liu, Y. H.; Mouikis, C. G.; Kistler, L. M.; Wang, S.; Roytershteyn, V.; Karimabadi, H.

    2015-05-01

    While the plasma in the Earth's magnetotail predominantly consists of protons and electrons, there are times when a significant amount of oxygen is present. When magnetic reconnection occurs, the behavior of these heavy ions can be significantly different from that of the protons, due to their larger gyroradius. In this study, we investigate the heavy ion distribution functions in the reconnection ion diffusion region from a 2.5D three-species particle-in-cell numerical simulation and compare those with Cluster observations from the near-Earth magnetotail. From the simulation results, we find that the heavy ions are demagnetized and accelerated in a larger diffusion region, the heavy ion diffusion region. The ion velocity distribution functions show that, inside the heavy ion diffusion region, heavy ions appear as counterstreaming beams along z in the GSM x-z plane, while drifting in y, carrying cross-tail current. We compare this result with Cluster observations in the vicinity of reconnection regions in the near-Earth magnetotail and find that the simulation predictions are consistent with the observed ion distribution functions in the ion diffusion region, as well as the inflow, exhaust, and separatrix regions. Based on the simulation and observation results, the presence of a multiscale diffusion region model, for O+ abundant reconnection events in the Earth's magnetotail, is demonstrated. A test particle simulation shows that in the diffusion region, the H+ gains energy mainly through Ex, while the O+ energy gain comes equally from Ex and Ey.

  12. Imposing long-range ferromagnetic order in rare-earth-doped magnetic topological-insulator heterostructures

    NASA Astrophysics Data System (ADS)

    Duffy, L. B.; Frisk, A.; Burn, D. M.; Steinke, N.-J.; Herrero-Martin, J.; Ernst, A.; van der Laan, G.; Hesjedal, T.

    2018-05-01

    The combination of topological properties and magnetic order can lead to new quantum states and exotic physical phenomena, such as the quantum anomalous Hall (QAH) effect. The size of the magnetic gap in the topological surface states, key for the robust observation of the QAH state, scales with the magnetic moment of the doped three-dimensional topological insulator (TI). The pioneering transition-metal doped (Sb,Bi ) 2(Se,Te ) 3 thin films only allow for the observation of the QAH effect up to some 100 mK, despite the much higher magnetic ordering temperatures. On the other hand, high magnetic moment materials, such as rare-earth-doped (Sb,Bi ) 2(Se,Te ) 3 thin films, show large moments but no long-range magnetic order. Proximity coupling and interfacial effects, multiplied in artificial heterostructures, allow for the engineering of the electronic and magnetic properties. Here, we show the successful growth of high-quality Dy:Bi2Te3 /Cr:Sb2Te3 thin film heterostructures. Using x-ray magnetic spectroscopy we demonstrate that high transition temperature Cr:Sb2Te3 can introduce long-range magnetic order in high-moment Dy:Bi2Te3 —up to a temperature of 17 K—in excellent agreement with first-principles calculations, which reveal the origin of the long-range magnetic order in a strong antiferromagnetic coupling between Dy and Cr magnetic moments at the interface extending over several layers. Engineered magnetic TI heterostructures may be an ideal materials platform for observing the QAH effect at liquid He temperatures and above.

  13. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1989-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  14. Compensation for effects of ambient temperature on rare-earth doped fiber optic thermometer

    NASA Technical Reports Server (NTRS)

    Adamovsky, G.; Sotomayor, J. L.; Krasowski, M. J.; Eustace, J. G.

    1990-01-01

    Variations in ambient temperature have a negative effect on the performance of any fiber optic sensing system. A change in ambient temperature may alter the design parameters of fiber optic cables, connectors, sources, detectors, and other fiber optic components and eventually the performance of the entire system. The thermal stability of components is especially important in a system which employs intensity modulated sensors. Several referencing schemes have been developed to account for the variable losses that occur within the system. However, none of these conventional compensating techniques can be used to stabilize the thermal drift of the light source in a system based on the spectral properties of the sensor material. The compensation for changes in ambient temperature becomes especially important in fiber optic thermometers doped with rare earths. Different approaches to solving this problem are searched and analyzed.

  15. Synthesis, Characterization and Comparative Luminescence Studies of Rare-Earth-Doped Gd2O3 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Pyngrope, D.; Singh, L. R.; Prasad, A. I.; Bora, A.

    2018-04-01

    A facile direct precipitation method was used for the synthesis of luminescence nanomaterial. Gd2O3 doped with rare earth element Eu3+ is synthesized by polyol route. The synthesized nanoparticles show their characteristic red emission. The nanoparticles are characterized by x-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and photoluminescence (PL) study. The synthesized nanoparticles are spherical particles with 30 nm size. The photoluminescence studies show the characteristic Eu3+ red emission. The PL study shows the intensity of the magnetic dipole transition ( 5 D0 \\to 7 F1 ) at 592 nm compared to that of the electronic dipole transition ( 5 D0 \\to 7 F2 ) at 615 nm. The nanomaterials can show significant application in various display devices and biomedical applications for tracking.

  16. In vivo demonstration of enhanced radiotherapy using rare earth doped titania nanoparticles†

    PubMed Central

    Townley, Helen E.; Kim, Jeewon; Dobson, Peter J.

    2017-01-01

    Radiation therapy is often limited by damage to healthy tissue and associated side-effects; restricting radiation to ineffective doses. Preferential incorporation of materials into tumour tissue can enhance the effect of radiation. Titania has precedent for use in photodynamic therapy (PDT), generating reactive oxygen species (ROS) upon photoexcitation, but is limited by the penetration depth of UV light. Optimization of a nanomaterial for interaction with X-rays could be used for deep tumour treatment. As such, titania nanoparticles were doped with gadolinium to optimize the localized energy absorption from a conventional medical X-ray, and further optimized by the addition of other rare earth (RE) elements. These elements were selected due to their large X-ray photon interaction cross-section, and potential for integration into the titania crystal structure. Specific activation of the nanoparticles by X-ray can result in generation of ROS leading to cell death in a tumour-localized manner. We show here that intratumoural injection of RE doped titania nanoparticles can enhance the efficacy of radiotherapy in vivo. PMID:22767269

  17. In vivo demonstration of enhanced radiotherapy using rare earth doped titania nanoparticles.

    PubMed

    Townley, Helen E; Kim, Jeewon; Dobson, Peter J

    2012-08-21

    Radiation therapy is often limited by damage to healthy tissue and associated side-effects; restricting radiation to ineffective doses. Preferential incorporation of materials into tumour tissue can enhance the effect of radiation. Titania has precedent for use in photodynamic therapy (PDT), generating reactive oxygen species (ROS) upon photoexcitation, but is limited by the penetration depth of UV light. Optimization of a nanomaterial for interaction with X-rays could be used for deep tumour treatment. As such, titania nanoparticles were doped with gadolinium to optimize the localized energy absorption from a conventional medical X-ray, and further optimized by the addition of other rare earth (RE) elements. These elements were selected due to their large X-ray photon interaction cross-section, and potential for integration into the titania crystal structure. Specific activation of the nanoparticles by X-ray can result in generation of ROS leading to cell death in a tumour-localized manner. We show here that intratumoural injection of RE doped titania nanoparticles can enhance the efficacy of radiotherapy in vivo.

  18. Molecular Dynamics Simulations of Ion-Doped Microphase Separated Diblock Copolymers

    NASA Astrophysics Data System (ADS)

    Seo, Youngmi; Brown, Jonathan R.; Hall, Lisa M.

    The effects of ion doping on microphase separated block copolymers are crucial to understand for transport applications such as battery electrolytes or fuel cell membranes. Prior experiments and theories have observed interesting trends, e.g. ions generally increase effective χ, broaden the domain interface at high loadings, and significantly change the order-to-disorder transition point. To provide a molecular level understanding of these trends and further information about ion dynamics, in this study, we perform molecular dynamics (MD) simulations using a generic coarse-grained model. We capture the selective ion solvation in one polymer microphase by adding an 1/r4 term to the intermolecular potential to account for the charge induced dipole effect between cations and A monomers. The model was validated by comparing with experimental domain spacing and density profile results. We find that as ions are added, the lamellar interface becomes sharper at first, then broadens with further ion loading, and finally forms a cylindrical morphology. We also observe that the interfacial broadening is retarded as the associative interaction between cations and A monomers or the ion-ion interaction strength is increased. These observations are compared to the results from fluids density functional theory (fDFT) which uses a similar model. We analyze ion dynamics in the model systems and discuss the impacts of ion selectivity and other variables on transport. This material is based upon work supported by the National Science Foundation under Grant 1454343.

  19. Luminescence properties of rare earth doped metal oxide nanostructures: A case of Eu-ZnO

    SciT

    Sahu, D.; Acharya, B. S.; Panda, N. R., E-mail: nihar@iitbbs.ac.in

    2016-05-06

    The present study reports the growth and luminescence properties of Eu doped ZnO nanostructures. The experiment has been carried out by synthesizing the materials by simple wet-chemical method. X-ray diffraction (XRD) studies show expansion of ZnO lattice with the incorporation of Eu ions which has been confirmed from the appearance of Eu{sub 2}O{sub 3} as a minor phase in the XRD pattern. The estimation of crystallite size from XRD results matches closely with the results obtained from transmission electron microscopy. Further, these results show the formation of nanosized Eu-ZnO particles of average size around 60 nm stacked on each other. FTIRmore » studies show the presence of both Zn-O and Eu-O modes in the spectra supporting the results obtained from XRD. The interesting results obtained from photoluminescence (PL) measurements show the presence of both band edge emission in UV region and the defect emissions in violet, blue and green region. The appearance of {sup 5}D{sub 0}→{sup 7}F{sub J} transitions of Eu{sup 3+} ions in red region clearly suggests the possible occurrence of energy transfer between the energy states of ZnO host and Eu{sup 3+} ions.« less

  20. Superior lithium adsorption and required magnetic separation behavior of iron-doped lithium ion-sieves

    SciT

    Wang, Shulei; Zheng, Shili; Wang, Zheming

    The recent research on adsorption-based lithium recovery from lithium-containing solutions has been centred on adsorption capacity and separation of lithium ion-sieves powder from solutions. Herein, an effective iron-doped lithium titanium oxide (Fe-doped Li 2TiO 3) was synthesized by Fe-doping via solid state reactions followed by acid treatment to form iron-doped lithium ion-sieves (Fe/Ti-x(H)). The resulting solid powder displays both superior adsorption capacity of lithium and high separation efficiency of the adsorbent from the solutions. SEM imaging and BET surface area measurement results showed that at Fe doping levels x ≤ 0.15, Fe-doping led to grain shrinkage as compared to Limore » 2TiO 3 and at the same time the BET surface area increased. The Fe/Ti-0.15(H) exhibited saturated magnetization values of 13.76 emu g -1, allowing effective separation of the material from solid suspensions through the use of a magnet. Consecutive magnetic separation results suggested that the Fe/Ti-0.15(H) powders could be applied at large-scale and continuously removed from LiOH solutions with separation efficiency of 96% or better. Lithium adsorption studies indicated that the equilibrium adsorption capacity of Fe/Ti-0.15(H) in LiOH solutions (1.8 g L -1 Li, pH 12) reached 53.3 mg g -1 within 24 h, which was higher than that of pristine Li 2TiO 3 (50.5 mg g-1) without Fe doping. Competitive adsorption and regeneration results indicated that the Fe/Ti-0.15(H) possessed a high selectivity for Li with facile regeneration. Therefore, it could be expected that the iron-doped lithium ion-sieves have practical applicability potential for large scale lithium extraction and recovery from lithium-bearing solutions.« less

  1. Superior lithium adsorption and required magnetic separation behavior of iron-doped lithium ion-sieves

    SciT

    Wang, Shulei; Zheng, Shili; Wang, Zheming

    The recent research on adsorption-based lithium recovery from lithium-containing solutions has been centred on adsorption capacity and separation of lithium ion-sieves powder from solutions. Herein, an effective iron-doped lithium titanium oxide (Fe-doped Li2TiO3) was synthesized by Fe-doping via solid state reactions followed by acid treatment to form iron-doped lithium ion-sieves (Fe/Ti-x(H)). The resulting solid powder displays both superior adsorption capacity of lithium and high separation efficiency of the adsorbent from the solutions. SEM imaging and BET surface area measurement results showed that at Fe doping levels x0.15, Fe-doping led to grain shrinkage as compared to Li2TiO3 and at the samemore » time the BET surface area increased. The Fe/Ti-0.15(H) exhibited saturated magnetization values of 13.76 emu g-1, allowing effective separation of the material from solid suspensions through the use of a magnet. Consecutive magnetic separation results suggested that the Fe/Ti-0.15(H) powders could be applied at large-scale and continuously removed from LiOH solutions with separation efficiency of 96% or better. Lithium adsorption studies indicated that the equilibrium adsorption capacity of Fe/Ti-0.15(H) in LiOH 2 solutions (1.8 g L-1 Li, pH 12) reached 53.3 mg g-1 within 24 h, which was higher than that of pristine Li2TiO3 (50.5 mg g-1) without Fe doping. Competitive adsorption and regeneration results indicated that the Fe/Ti-0.15(H) possessed a high selectivity for Li with facile regeneration. Therefore, it could be expected that the iron-doped lithium ion-sieves have practical applicability potential for large scale lithium extraction and recovery from lithium-bearing solutions.« less

  2. Superior lithium adsorption and required magnetic separation behavior of iron-doped lithium ion-sieves

    DOE PAGES

    Wang, Shulei; Zheng, Shili; Wang, Zheming; ...

    2018-09-09

    The recent research on adsorption-based lithium recovery from lithium-containing solutions has been centred on adsorption capacity and separation of lithium ion-sieves powder from solutions. Herein, an effective iron-doped lithium titanium oxide (Fe-doped Li 2TiO 3) was synthesized by Fe-doping via solid state reactions followed by acid treatment to form iron-doped lithium ion-sieves (Fe/Ti-x(H)). The resulting solid powder displays both superior adsorption capacity of lithium and high separation efficiency of the adsorbent from the solutions. SEM imaging and BET surface area measurement results showed that at Fe doping levels x ≤ 0.15, Fe-doping led to grain shrinkage as compared to Limore » 2TiO 3 and at the same time the BET surface area increased. The Fe/Ti-0.15(H) exhibited saturated magnetization values of 13.76 emu g -1, allowing effective separation of the material from solid suspensions through the use of a magnet. Consecutive magnetic separation results suggested that the Fe/Ti-0.15(H) powders could be applied at large-scale and continuously removed from LiOH solutions with separation efficiency of 96% or better. Lithium adsorption studies indicated that the equilibrium adsorption capacity of Fe/Ti-0.15(H) in LiOH solutions (1.8 g L -1 Li, pH 12) reached 53.3 mg g -1 within 24 h, which was higher than that of pristine Li 2TiO 3 (50.5 mg g-1) without Fe doping. Competitive adsorption and regeneration results indicated that the Fe/Ti-0.15(H) possessed a high selectivity for Li with facile regeneration. Therefore, it could be expected that the iron-doped lithium ion-sieves have practical applicability potential for large scale lithium extraction and recovery from lithium-bearing solutions.« less

  3. Fe doped Magnetic Nanodiamonds made by Ion Implantation.

    PubMed

    Chen, ChienHsu; Cho, I C; Jian, Hui-Shan; Niu, H

    2017-02-09

    Here we present a simple physical method to prepare magnetic nanodiamonds (NDs) using high dose Fe ion-implantation. The Fe atoms are embedded into NDs through Fe ion-implantation and the crystal structure of NDs are recovered by thermal annealing. The results of TEM and Raman examinations indicated the crystal structure of the Fe implanted NDs is recovered completely. The SQUID-VSM measurement shows the Fe-NDs possess room temperature ferromagnetism. That means the Fe atoms are distributed inside the NDs without affecting NDs crystal structure, so the NDs can preserve the original physical and chemical properties of the NDs. In addition, the ion-implantation-introduced magnetic property might make the NDs to become suitable for variety of medical applications.

  4. Fe doped Magnetic Nanodiamonds made by Ion Implantation

    NASA Astrophysics Data System (ADS)

    Chen, Chienhsu; Cho, I. C.; Jian, Hui-Shan; Niu, H.

    2017-02-01

    Here we present a simple physical method to prepare magnetic nanodiamonds (NDs) using high dose Fe ion-implantation. The Fe atoms are embedded into NDs through Fe ion-implantation and the crystal structure of NDs are recovered by thermal annealing. The results of TEM and Raman examinations indicated the crystal structure of the Fe implanted NDs is recovered completely. The SQUID-VSM measurement shows the Fe-NDs possess room temperature ferromagnetism. That means the Fe atoms are distributed inside the NDs without affecting NDs crystal structure, so the NDs can preserve the original physical and chemical properties of the NDs. In addition, the ion-implantation-introduced magnetic property might make the NDs to become suitable for variety of medical applications.

  5. On the origins of energetic ions in the earth's dayside magnetosheath

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.; Klumpar, D. M.; Shelley, E. G.

    1991-01-01

    Energetic ion events in the earth's dayside subsolar magnetosheath (0900 - 1300 Local Time) are surveyed using data from the AMPTE/CCE Hot Plasma Composition Experiment. Ion species carrying the signature of their origin O(+) and energetic He(2+) are used to distinguish between magnetospheric and solar wind origins for the energetic ion events. The results of this survey indicate that the majority of energetic (10-17 keV/e) H(+) and He(2+) ions observed in the dayside magnetosheath are accelerated from the solar wind population. The energetic He(2+) to H(+) density ratio in the magnetosheath is consistent with that predicted from first-order Fermi acceleration of solar wind ions in the turbulent regions upstream and downstream from the earth's quasi-parallel bow shock. The simultaneous occurrence of both energetic He(2+) and magnetospheric O(+) indicates that, on occasion, both Fermi acceleration of solar wind ions and leakage of magnetospheric ions occurs in the dayside magnetosheath.

  6. Ion Correlation Effects in Salt-Doped Block Copolymers

    NASA Astrophysics Data System (ADS)

    Brown, Jonathan R.; Seo, Youngmi; Hall, Lisa M.

    2018-03-01

    We apply classical density functional theory to study how salt changes the microphase morphology of diblock copolymers. Polymers are freely jointed and one monomer type favorably interacts with ions, to account for the selective solvation that arises from different dielectric constants of the microphases. By including correlations from liquid state theory of an unbound reference fluid, the theory can treat chain behavior, microphase separation, ion correlations, and preferential solvation, at the same coarse-grained level. We show good agreement with molecular dynamics simulations.

  7. NREL, NASA, and UCL Team Up to Make Lithium-Ion Batteries Safer on Earth

    and in Space | News | NREL NREL, NASA, and UCL Team Up to Make Lithium-Ion Batteries Safer on Earth and in Space NREL, NASA, and UCL Team Up to Make Lithium-Ion Batteries Safer on Earth and in Space . NREL joined forces with NASA in finding new, more precise ways to trigger internal short circuits

  8. Synthesis and evaluation of rare-earth doped glasses and crystals for optical refrigeration

    NASA Astrophysics Data System (ADS)

    Patterson, Wendy

    This research focused on developing and characterizing rare-earth doped, solid-state materials for laser cooling. In particular, the work targeted the optimization of the lasercooling efficiency in Yb3+ and Tm3+ doped fluorides. The first instance of laser-induced cooling in a Tm3+-doped crystal, BaY2F8 was reported. Cooling by 3 degrees Kelvin below ambient temperature was obtained in a single-pass pump geometry at lambda = 1855 nm. Protocols were developed for materials synthesis and purification which can be applied to each component of ZBLANI:Yb 3+/Tm3+ (ZrF4 -- BaF2 -- LaF3 -- AlF3 -- NaF -- InF3: YbF3/TmF3) glass to enable a material with significantly reduced transition-metal impurities. A method for OH- impurity removal and ultra-drying of the metal fluorides was also improved upon. Several characterization tools were used to quantitatively and qualitatively verify purity, including inductively-coupled plasma mass spectrometry (ICP-MS). Here we found a more than 600-fold reduction in transition-metal impurities in a ZrCl2O solution. A non-contact spectroscopic technique for the measurement of laser-induced temperature changes in solids was developed. Two-band differential luminescence thermometry (TBDLT) achieved a sensitivity of ˜7 mK and enabled precise measurement of the zero-crossing temperature and net quantum efficiency. Several Yb3+-doped ZBLANI glasses fabricated from precursors of varying purity and by different processes were analyzed in detail by TBDLT. Laser-induced cooling was observed at room temperature for several of the materials. A net quantum efficiency of 97.39+/-0.01% at 238 K was found for the best ZBLANI:1%Yb 3+ laser-cooling sample produced from purified metal-fluoride precursors, and proved competitive with the best commercially procured material. The TBDLT technique enabled rapid and sensitive benchmarking of laser-cooling materials and provided critical feedback to the development and optimization of high-performance optical

  9. Luminescence properties of Sm3+-doped alkaline earth ortho-stannates

    NASA Astrophysics Data System (ADS)

    Stanulis, Andrius; Katelnikovas, Artūras; Enseling, David; Dutczak, Danuta; Šakirzanovas, Simas; Bael, Marlies Van; Hardy, An; Kareiva, Aivaras; Jüstel, Thomas

    2014-05-01

    A series of Sm3+ doped M2SnO4 (M = Ca, Sr and Ba) samples were prepared by a conventional high temperature solid-state reaction route. All samples were characterized by powder X-ray diffraction (XRD) analysis, photoluminescence (PL), photoluminescence thermal quenching (TQ) and fluorescence lifetime (FL) measurements. The morphology of synthesized phosphor powders was examined by scanning electron microscopy (SEM). Moreover, luminous efficacies (LE) and color points of the CIE 1931 color space diagram were calculated and discussed. Synthesized powders showed bright orange-red emission under UV excitation. Based on the results obtained we demonstrate that Sm3+ ions occupy Ca and Sr sites in the Ca2SnO4 and Sr2SnO4 ortho-stannate structures, respectively. In contrast, Sm3+ substitutes Sn in the barium ortho-stannate Ba2SnO4 structure.

  10. High Capacity of Hard Carbon Anode in Na-Ion Batteries Unlocked by PO x Doping

    SciT

    Li, Zhifei; Ma, Lu; Surta, Todd Wesley

    2016-08-12

    The capacity of hard carbon anodes in Na-ion batteries 2.5 rarely reaches values beyond 300 mAh/g. We report that doping POx into local structures of hard carbon increases its reversible capacity from 283 to 359 mAh/g. We confirm that the doped POx is redox inactive by X-ray adsorption near edge structure measurements, thus not contributing to the higher capacity. We observe two significant changes of hard carbon's local structures caused by doping. First, the (002) d-spacing inside the turbostratic nanodomains is increased, revealed by both laboratory and synchrotron X-ray diffraction. Second, doping turns turbostratic nanodomains more defective along ab planes,more » indicated by neutron total scattering and the associated pair distribution function studies. The local structural changes of hard carbon are correlated to the higher capacity, where both the plateau and slope regions in the potential profiles are enhanced. Our study demonstrates that Na-ion storage in hard carbon heavily depends on carbon local structures, where such structures, despite being disordered, can be tuned toward unusually high capacities.« less

  11. Solution Synthesis of Iodine-Doped Red Phosphorus Nanoparticles for Lithium-Ion Battery Anodes.

    PubMed

    Chang, Wei-Chung; Tseng, Kuan-Wei; Tuan, Hsing-Yu

    2017-02-08

    Red phosphorus (RP) is a promising anode material for lithium-ion batteries due to its earth abundance and a high theoretical capacity of 2596 mA h g -1 . Although RP-based anodes for lithium-ion batteries have been reported, they were all in the form of carbon-P composites, including P-graphene, P-graphite, P-carbon nanotubes (CNTs), and P-carbon black, to improve P's extremely low conductivity and large volume change during cycling process. Here, we report the large-scale synthesis of red phosphorus nanoparticles (RPNPs) with sizes ranging from 100 to 200 nm by reacting PI 3 with ethylene glycol in the presence of cetyltrimethylammonium bromide (CTAB) in ambient environment. Unlike the insulator behavior of commercial RP (conductivity of <10 -12 S m -1 ), the conductivity of RPNPs is between 2.62 × 10 -3 and 1.81 × 10 -2 S m -1 , which is close to that of semiconductor germanium (1.02 × 10 -2 S m -1 ), and 2 orders of magnitude higher than silicon (5.35 × 10 -4 S m -1 ). Around 3-5 wt % of iodine-doping was found in RPNPs, which was speculated as the key to significantly improve the conductivity of RPNPs. The significantly improved conductivity of RPNPs and their uniform colloidal nanostructures enable them to be used solely as active materials for LIBs anodes. The RPNPs electrodes exhibit a high specific capacity of 1700 mA h g -1 (0.2 C after 100 cycles, 1 C = 2000 mA g -1 ), long cycling life (∼900 mA h g -1 after 500 cycles at 1 C), and outstanding rate capability (175 mA h g -1 at the charge current density of 120 A g -1 , 60 C). Moreover, as a proof-of-concept example, pouch-type full cells using RPNPs anodes and Li(Ni 0.5 Co 0.3 Mn 0.2 )O 2 (NCM-532) cathodes were assembled to show their practical uses.

  12. Assessment of effect of Yb3+ ion pairs on a highly Yb-doped double-clad fibre laser

    NASA Astrophysics Data System (ADS)

    Vallés, J. A.; Martín, J. C.; Berdejo, V.; Cases, R.; Álvarez, J. M.; Rebolledo, M. Á.

    2018-03-01

    Using a previously validated characterization method based on the careful measurement of the characteristic parameters and fluorescence emission spectra of a highly Yb-doped double-clad fibre, we evaluate the contribution of ion pair induced processes to the output power of a double-clad Yb-doped fibre ring laser. This contribution is proved to be insignificant, contrary to analysis by other authors, who overestimate the role of ion pairs.

  13. Enhancing optical gains in Si nanocrystals via hydrogenation and cerium ion doping

    SciT

    Wang, Dong-Chen; Li, Yan-Li; Song, Sheng-Chi

    We report optical gain enhancements in Si nanocrystals (Si-NCs) via hydrogenation and Ce{sup 3+} ion doping. Variable stripe length technique was used to obtain gains. At 0.3 W/cm{sup 2} pumping power density of pulsed laser, net gains were observed together with gain enhancements after hydrogenation and/or Ce{sup 3+} ion doping; gains after loss corrections were between 89.52 and 341.95 cm{sup −1}; and the photoluminescence (PL) lifetime was found to decrease with the increasing gain enhancement. At 0.04 W/cm{sup 2} power density, however, no net gain was found and the PL lifetime increased with the increasing PL enhancement. The results were discussed according tomore » stimulated and spontaneous excitation and de-excitation mechanisms of Si-NCs.« less

  14. Structural and photocatalytic studies on pure and Sn ion doped ZnO-graphene nanocomposites

    NASA Astrophysics Data System (ADS)

    Beura, Rosalin; Thangadurai, P.

    2016-05-01

    Graphene based metal oxide nanocomposites have been widely used as a photocatalyst for the treatment of water pollutants. This work demonstrates the synthesis of graphene composite with pure and Sn ion doped-ZnO and their photocatalytic properties are reported. Structural studies were carried out by X-ray diffraction and Raman spectroscopy to confirm the formation of the nanocomposites. Microstructure was characterized by scanning electron microscopy showing rod shaped ZnO and the layer structured graphene in the ZnO-graphene composite. In comparison with the undoped ZnO-graphene composite, the Sn ion doped ZnO-graphene composite have shown better degradation of methyl orange dye that is about 99% of degradation. Band gap of the composite materials was calculated to be 3.36 eV from the UV-Vis result.

  15. Structural and photocatalytic studies on pure and Sn ion doped ZnO-graphene nanocomposites

    SciT

    Beura, Rosalin; Thangadurai, P., E-mail: thangaduraip.nst@pondiuni.edu.in

    2016-05-23

    Graphene based metal oxide nanocomposites have been widely used as a photocatalyst for the treatment of water pollutants. This work demonstrates the synthesis of graphene composite with pure and Sn ion doped-ZnO and their photocatalytic properties are reported. Structural studies were carried out by X-ray diffraction and Raman spectroscopy to confirm the formation of the nanocomposites. Microstructure was characterized by scanning electron microscopy showing rod shaped ZnO and the layer structured graphene in the ZnO-graphene composite. In comparison with the undoped ZnO-graphene composite, the Sn ion doped ZnO-graphene composite have shown better degradation of methyl orange dye that is aboutmore » 99% of degradation. Band gap of the composite materials was calculated to be 3.36 eV from the UV-Vis result.« less

  16. The Role of Dopant Ions on Charge Injection and Transport in Electrochemically Doped Quantum Dot Films

    PubMed Central

    2018-01-01

    Control over the charge density is very important for implementation of colloidal semiconductor nanocrystals into various optoelectronic applications. A promising approach to dope nanocrystal assemblies is charge injection by electrochemistry, in which the charge compensating electrolyte ions can be regarded as external dopant ions. To gain insight into the doping mechanism and the role of the external dopant ions, we investigate charge injection in ZnO nanocrystal assemblies for a large series of charge compensating electrolyte ions with spectroelectrochemical and electrochemical transistor measurements. We show that charge injection is limited by the diffusion of cations in the nanocrystal films as their diffusion coefficient are found to be ∼7 orders of magnitude lower than those of electrons. We further show that the rate of charge injection depends strongly on the cation size and cation concentration. Strikingly, the onset of electron injection varies up to 0.4 V, depending on the size of the electrolyte cation. For the small ions Li+ and Na+ the onset is at significantly less negative potentials. For larger ions (K+, quaternary ammonium ions) the onset is always at the same, more negative potential, suggesting that intercalation may take place for Li+ and Na+. Finally, we show that the nature of the charge compensating cation does not affect the source-drain electronic conductivity and mobility, indicating that shallow donor levels from intercalating ions fully hybridize with the quantum confined energy levels and that the reorganization energy due to intercalating ions does not strongly affect electron transport in these nanocrystal assemblies. PMID:29718666

  17. Luminescence studies of rare earth doped yttrium gadolinium mixed oxide phosphor

    NASA Astrophysics Data System (ADS)

    Som, S.; Choubey, A.; Sharma, S. K.

    2012-09-01

    This paper reports the photoluminescence and thermoluminescence properties of gamma ray induced rare earth doped yttrium gadolinium mixed oxide phosphor. The europium (Eu3+) was used as rare earth dopant. The phosphor was prepared by chemical co-precipitation method according to the formula (Y2-x-yGdx) O3: Euy3+ (x=0.5; y=0.05). The photoluminescence emission spectrum of the prepared phosphor shows intense peaks in the red region at 615 nm for 5D0→7F2 transitions and the photoluminescence excitation spectra show a broad band located around 220-270 nm for the emission wavelength fixed at 615 nm. The thermoluminescence studies were carried out after irradiating the phosphor by gamma rays in the dose range from 100 Gy to 1 KGy. In the thermoluminescence glow curves, one single peak was observed at about 300 °C of which the intensity increases linearly in the studied dose range of gamma rays. The glow peak was deconvoluted by GlowFit program and the kinetic parameters associated with the deconvoluted peaks were calculated. The kinetic parameters were also calculated by various glow curve shape and heating rate methods.

  18. The influence of Mg doping on the formation of Ga vacancies and negative ions in GaN bulk crystals

    NASA Astrophysics Data System (ADS)

    Saarinen, K.; Nissilä, J.; Hautojärvi, P.; Likonen, J.; Suski, T.; Grzegory, I.; Lucznik, B.; Porowski, S.

    1999-10-01

    Gallium vacancies and negative ions are observed in GaN bulk crystals by applying positron lifetime spectroscopy. The concentration of Ga vacancies decreases with increasing Mg doping, as expected from the behavior of the VGa formation energy as a function of the Fermi level. The concentration of negative ions correlates with that of Mg impurities determined by secondary ion mass spectrometry. We thus attribute the negative ions to MgGa-. The negative charge of Mg suggests that Mg doping converts n-type GaN to semi-insulating mainly due to the electrical compensation of ON+ donors by MgGa- acceptors.

  19. Ion-doping as a strategy to modulate hydroxyapatite nanoparticle internalization

    NASA Astrophysics Data System (ADS)

    Zhao, Z.; Espanol, M.; Guillem-Marti, J.; Kempf, D.; Diez-Escudero, A.; Ginebra, M.-P.

    2016-01-01

    Although it is widely acknowledged that ionic substitutions on bulk hydroxyapatite substrates have a strong impact on their biological performance, little is known of their effect on nanoparticles (NPs) especially when used for gene transfection or drug delivery. The fact that NPs would be internalized poses many questions but also opens up many new possibilities. The objective of the present work is to synthesize and assess the effect of a series of hydroxyapatite-like (HA) NPs doped with various ions on cell behavior, i.e. carbonate, magnesium and co-addition. We synthesized NPs under similar conditions to allow comparison of results and different aspects in addition to assessing the effect of the doping ion(s) were investigated: (1) the effect of performing the cell culture study on citrate-dispersed NPs and on agglomerated NPs, (2) the effect of adding/excluding 10% of foetal bovine serum (FBS) in the cell culture media and (3) the type of cell, i.e. MG-63 versus rat mesenchymal stem cells (rMSCs). The results clearly demonstrated that Mg-doping had a major effect on MG-63 cells with high cytotoxicity but not to rMSCs. This was a very important finding because it proved that doping could be a tool to modify NP internalization. The results also suggest that NP surface charge had a large impact on MG-63 cells and prevents their internalization if it is too negative--this effect was less critical for rMSCs.Although it is widely acknowledged that ionic substitutions on bulk hydroxyapatite substrates have a strong impact on their biological performance, little is known of their effect on nanoparticles (NPs) especially when used for gene transfection or drug delivery. The fact that NPs would be internalized poses many questions but also opens up many new possibilities. The objective of the present work is to synthesize and assess the effect of a series of hydroxyapatite-like (HA) NPs doped with various ions on cell behavior, i.e. carbonate, magnesium and co

  20. On the possibility of laser cooling of Cr3+ ions doped crystals

    NASA Astrophysics Data System (ADS)

    Feofilov, S. P.; Kulinkin, A. B.

    2018-01-01

    The fluorescence of Cr3+ ions doped insulating crystals was studied under the excitation in the long-wavelength tail of the absorption spectrum ("laser cooling regime"). The 4T2 - 4A2 and 2E - 4A2 fluorescence spectra with a dominant anti-Stokes component were observed. Though no optical refrigeration was detected in the presented experiments, the spectroscopic results suggest that electron-phonon bands of Cr3+ ions are of interest for further investigations from the point of view of achieving optical refrigeration.

  1. X-ray-induced fluorescent centers formation in zinc- phosphate glasses doped with Ag and Cu ions

    NASA Astrophysics Data System (ADS)

    Klyukin, D. A.; Pshenova, A. S.; Sidorov, A. I.; Stolyarchuk, M. V.

    2016-08-01

    Fluorescent properties of silver and copper doped zinc-phosphate glasses were studied. By X-ray irradiation of silver and copper co-doped glasses we could create and identify new emission centers which do not exist in single-doped samples. Doping of the glass with both silver and copper ions leads to the increase of quantum yield by 2.7 times. The study was complemented by quantum chemical calculations using the time-dependent density functional theory. It was shown that fluorescence may be attributed to the formation of mixed Ag-Cu molecular clusters.

  2. Evidence of dilute ferromagnetism in rare-earth doped yttrium aluminium garnet

    SciT

    Farr, Warrick G.; Goryachev, Maxim; Le Floch, Jean-Michel

    This work demonstrates strong coupling regime between an erbium ion spin ensemble and microwave hybrid cavity-whispering gallery modes in a yttrium aluminium garnet dielectric crystal. Coupling strengths of 220 MHz and mode quality factors in excess of 10{sup 6} are demonstrated. Moreover, the magnetic response of high-Q modes demonstrates behaviour which is unusual for paramagnetic systems. This behaviour includes hysteresis and memory effects. Such qualitative change of the system's magnetic field response is interpreted as a phase transition of rare earth ion impurities. This phenomenon is similar to the phenomenon of dilute ferromagnetism in semiconductors. The clear temperature dependence of themore » phenomenon is demonstrated.« less

  3. Rare earth-doped barium gallo-germanate glasses and their near-infrared luminescence properties.

    PubMed

    Pisarska, Joanna; Sołtys, Marta; Górny, Agata; Kochanowicz, Marcin; Zmojda, Jacek; Dorosz, Jan; Dorosz, Dominik; Sitarz, Maciej; Pisarski, Wojciech A

    2018-08-05

    Near-infrared luminescence properties of Nd 3+ and Ho 3+ ions in barium gallo-germanate glasses have been reported. Several spectroscopic parameters for Nd 3+ and Ho 3+ ions have been determined from the Judd-Ofelt analysis and absorption/luminescence measurements. Quite large luminescence lifetime, quantum efficiency and stimulated emission cross-section have been obtained for the main 4 F 3/2  →  4 I 11/2 (Nd 3+ ) and 5 I 7  →  5 I 8 (Ho 3+ ) laser transitions of rare earths in barium gallo-germanate glasses. It suggests that barium gallo-germanate glass is promising for near-infrared laser application at emission wavelengths 1064 nm (Nd 3+ ) and 2020 nm (Ho 3+ ). Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Lithium metal doped electrodes for lithium-ion rechargeable chemistry

    DOEpatents

    Liu, Gao; Battaglia, Vince; Wang, Lei

    2016-09-13

    An embodiment of the invention combines the superior performance of a polyvinylidene difluoride (PVDF) or polyethyleneoxide (POE) binder, the strong binding force of a styrene-butadiene (SBR) binder, and a source of lithium ions in the form of solid lithium metal powder (SLMP) to form an electrode system that has improved performance as compared to PVDF/SBR binder based electrodes. This invention will provide a new way to achieve improved results at a much reduced cost.

  5. Temperature dependent mobility measurements of alkali earth ions in superfluid helium

    NASA Astrophysics Data System (ADS)

    Putlitz, Gisbert Zu; Baumann, I.; Foerste, M.; Jungmann, K.; Riediger, O.; Tabbert, B.; Wiebe, J.; Zühlke, C.

    1998-05-01

    Mobility measurements of impurity ions in superfluid helium are reported. Alkali earth ions were produced with a laser sputtering technique and were drawn inside the liquid by an electric field. The experiments were carried out in the temperature region from 1.27 up to 1.66 K. The temperature dependence of the mobility of Be^+-ions (measured here for the first time) differs from that of the other alkali earth ions Mg^+, Ca^+, Sr^+ and Ba^+, but behaves similar to that of He^+ (M. Foerste, H. Günther, O. Riediger, J. Wiebe, G. zu Putlitz, Z. Phys. B) 104, 317 (1997). Theories of Atkins (A. Atkins, Phys. Rev.) 116, 1339 (1959) and Cole (M.W. Cole, R.A. Bachmann Phys. Rev. B) 15, 1388 (1977) predict a different defect structure for He^+ and the alkali earth ions: the helium ion is assumed to form a snowball like structure whereas for the alkali earth ions a bubble structure is assumed. If the temperature dependence is a characteristic feature for the different structures, then it seems likely that the Be^+ ion builds a snowball like structure.

  6. Ionic Liquid-Doped Gel Polymer Electrolyte for Flexible Lithium-Ion Polymer Batteries

    PubMed Central

    Zhang, Ruisi; Chen, Yuanfen; Montazami, Reza

    2015-01-01

    Application of gel polymer electrolytes (GPE) in lithium-ion polymer batteries can address many shortcomings associated with liquid electrolyte lithium-ion batteries. Due to their physical structure, GPEs exhibit lower ion conductivity compared to their liquid counterparts. In this work, we have investigated and report improved ion conductivity in GPEs doped with ionic liquid. Samples containing ionic liquid at a variety of volume percentages (vol %) were characterized for their electrochemical and ionic properties. It is concluded that excess ionic liquid can damage internal structure of the batteries and result in unwanted electrochemical reactions; however, samples containing 40–50 vol % ionic liquid exhibit superior ionic properties and lower internal resistance compared to those containing less or more ionic liquids.

  7. The Role of Defect Complexes in the Magneto-Optical Properties of Rare Earth Doped Gallium Nitride

    NASA Astrophysics Data System (ADS)

    Mitchell, Brandon

    Wide band gap semiconductors doped with rare earth ions (RE) have shown great potential for applications in optoelectronics, photonics, and spintronics. The 1.54mum Erbium (Er) emission has been extensively utilized in optical fiber communications, and Europium (Eu) is commonly used as a red color component for LEDs and fluorescence lamps. For the realization of spintronic-type devices, a dilutely doped semiconductor that exhibits room temperature ferromagnetic behavior would be desirable. Such behavior has been observed in GaN:Er. Furthermore, it was demonstrated that strain may play an important role in the control of this ferromagnetism; however, this requires further investigation. One motivation of this work is the realization of an all solid state white light source monolithically integrated into III/V nitride semiconductor materials, ideally GaN. For this, the current AlGaAs-based LEDs need to be replaced. One approach for achieving efficient red emission from GaN is dilute doping with fluorescent ions. In this regard, Eu has consistently been the most promising candidate as a dopant in the active layer for a red, GaN based, LED due to the sharp 5D0 to 7F2 transitions that result in red emission around 620nm. The success of GaN:Eu as the active layer for a red LED is based on the ability for the Eu ions to be efficiently excited by electron hole pairs. Thus, the processes by which energy is transferred from the host to the Eu ions has been studied. Complications arise, however, from the fact that Eu ions incorporate into multiple center environments, the structures of which are found to have a profound influence on the excitation pathways and efficiencies of the Eu ion. Therefore the nature of Eu incorporation and the resulting luminescence efficiency in GaN has been extensively investigated. By performing a comparative study on GaN:Eu samples grown under a variety of controlled conditions and using a variety of experimental techniques, the majority site has

  8. A study of the formation and dynamics of the Earth's plasma sheet using ion composition data

    NASA Technical Reports Server (NTRS)

    Lennartsson, O. W.

    1994-01-01

    Over two years of data from the Lockheed Plasma Composition Experiment on the ISEE 1 spacecraft, covering ion energies between 100 eV/e and about 16 keV/e, have been analyzed in an attempt to extract new information about three geophysical issues: (1) solar wind penetration of the Earth's magnetic tail; (2) relationship between plasma sheet and tail lobe ion composition; and (3) possible effects of heavy terrestrial ions on plasma sheet stability.

  9. METHOD OF SEPARATING RARE EARTHS BY ION EXCHANGE

    DOEpatents

    Spedding, F.H.; Powell, J.E.

    1960-10-18

    A process is given for separating yttrium and rare earth values having atomic numbers of from 57 through 60 and 68 through 71 from an aqueous solution whose pH value can range from 1 to 9. All rare earths and yttrium are first adsorbed on a cation exchange resin, and they are then eluted with a solution of N-hydroxyethylethylenediaminetriacetic acid (HEDTA) in the order of decreasing atomic number, yttrium behaving like element 61; the effluents are collected in fractions. The HEDTA is recovered by elution with ammonia solution and the resin is regenerated with sulfuric acid. Rare earths are precipitated from the various effluents with oxalic acid, and each supernatant is passed over cation exchange resin for adsorption of HEDTA and nonprecipitated rare earths: the oxalic acid is not retained by the resin.

  10. Enhanced etching of tin-doped indium oxide due to surface modification by hydrogen ion injection

    NASA Astrophysics Data System (ADS)

    Li, Hu; Karahashi, Kazuhiro; Friederich, Pascal; Fink, Karin; Fukasawa, Masanaga; Hirata, Akiko; Nagahata, Kazunori; Tatsumi, Tetsuya; Wenzel, Wolfgang; Hamaguchi, Satoshi

    2018-06-01

    It is known that the etching yield (i.e., sputtering yield) of tin-doped indium oxide (ITO) by hydrocarbon ions (CH x +) is higher than its corresponding physical sputtering yield [H. Li et al., J. Vac. Sci. Technol. A 33, 060606 (2015)]. In this study, the effects of hydrogen in the incident hydrocarbon ion beam on the etching yield of ITO have been examined experimentally and theoretically with the use of a mass-selected ion beam system and by first-principles quantum mechanical (QM) simulation. As in the case of ZnO [H. Li et al., J. Vac. Sci. Technol. A 35, 05C303 (2017)], mass-selected ion beam experiments have shown that the physical sputtering yield of ITO by chemically inert Ne ions increases after a pretreatment of the ITO film by energetic hydrogen ion injection. First-principles QM simulation of the interaction of In2O3 with hydrogen atoms shows that hydrogen atoms embedded in In2O3 readily form hydroxyl (OH) groups and weaken or break In–O bonds around the hydrogen atoms, making the In2O3 film less resistant to physical sputtering. This is consistent with experimental observation of the enhanced etching yields of ITO by CH x + ions, considering the fact that hydrogen atoms of the incident CH x + ions are embedded into ITO during the etching process.

  11. Rare-Earth Doping and Co-Doping of GaN for Magnetic and Luminescent Applications

    DTIC Science & Technology

    2010-08-16

    The main focus of this project is the study of Gadolinium doped Gallium Nitride. Calculations were carried out to elucidate the origin of the reported...Ga vacancies in the triple negative charge state, which is the most likely charge state in semi-insulating samples, 1. REPORT DATE (DD-MM-YYYY) 4...applications Report Title ABSTRACT The main focus of this project is the study of Gadolinium doped Gallium Nitride. Calculations were carried out to

  12. Spectroscopy and energy transfer in lead borate glasses doubly doped with Tm3+ and Dy3+ ions

    NASA Astrophysics Data System (ADS)

    Górny, Agata; Sołtys, Marta; Pisarska, Joanna; Pisarski, Wojciech A.

    2018-03-01

    Lead borate glasses singly and doubly doped with Tm3+ and Dy3+ were prepared by traditional melt-quenching technique. The emission spectra of rare earths in studied glass systems were registered under different excitation wavelengths. The observed emission bands are located in the visible spectral region. They correspond to 1D2 → 3F4 (blue) and 1G4 → 3H6 (blue) transitions of Tm3+ as well as 4F9/2 → 6H15/2 (blue), 4F9/2 → 6H13/2 (yellow) and 4F9/2 → 6H11/2 (red) transitions of Dy3+. Moreover, the energy transfer process from Tm3+ to Dy3+ was observed. The luminescence bands originating to characteristic transitions of thulium and dysprosium ions are present on emission spectra under direct excitation of Tm3+. Luminescence lifetimes for the excited states of Tm3+ and Dy3+ ions in lead borate glass were also determined based on decay measurements. The luminescence intensities and lifetimes depend significantly on the relative concentrations of the optically active dopants.

  13. Oxygen ion transference number of doped lanthanum gallate

    NASA Astrophysics Data System (ADS)

    Wang, Shizhong; Wu, Lingli; Gao, Jie; He, Qiong; Liu, Meilin

    The transference numbers for oxygen ion (t O) in several LaGaO 3-based materials are determined from oxygen concentration cells using the materials as the electrolyte, including La 0.8Sr 0.2Ga 0.8Mg 0.2O 3- δ (LSGM8282), La 0.8Sr 0.2Ga 0.8Mg 0.15Co 0.05O 3- δ (LSGMC5) and La 0.8Sr 0.2Ga 0.8Mg 0.115Co 0.085O 3- δ (LSGMC8.5). Analysis indicates that the accuracy in determination of oxygen ion transference number depends on the electrode polarization resistances of the concentration cell as well as the transport properties of the materials studied. For example, the ratio of open cell voltage to Nernst potential is a good approximation to the ionic transference number for LSGM8282. However, this approximation is no longer adequate for LSGMC5 and LSGMC8.5; the effect of electrode polarization resistances must be taken into consideration in estimation of the ionic transference numbers. In particular, the ionic transference number for LSGMC5 is as high as 0.99, suggesting that it is a promising electrolyte material for low-temperature solid-state electrochemical applications.

  14. Modifying the size and uniformity of upconversion Yb/Er:NaGdF4 nanocrystals through alkaline-earth doping.

    PubMed

    Lei, Lei; Chen, Daqin; Huang, Ping; Xu, Ju; Zhang, Rui; Wang, Yuansheng

    2013-11-21

    NaGdF4 is regarded as an ideal upconversion (UC) host material for lanthanide (Ln(3+)) activators because of its unique crystal structure, high Ln(3+) solubility, low phonon energy and high photochemical stability, and Ln(3+)-doped NaGdF4 UC nanocrystals (NCs) have been widely investigated as bio-imaging and magnetic resonance imaging agents recently. To realize their practical applications, controlling the size and uniformity of the monodisperse Ln(3+)-doped NaGdF4 UC NCs is highly desired. Unlike the routine routes by finely adjusting the multiple experimental parameters, herein we provide a facile and straightforward strategy to modify the size and uniformity of NaGdF4 NCs via alkaline-earth doping for the first time. With the increase of alkaline-earth doping content, the size of NaGdF4 NCs increases gradually, while the size-uniformity is still retained. We attribute this "focusing" of size distribution to the diffusion controlled growth of NaGdF4 NCs induced by alkaline-earth doping. Importantly, adopting the Ca(2+)-doped Yb/Er:NaGdF4 NCs as cores, the complete Ca/Yb/Er:NaGdF4@NaYF4 core-shell particles with excellent size-uniformity can be easily achieved. However, when taking the Yb/Er:NaGdF4 NCs without Ca(2+) doping as cores, they could not be perfectly covered by NaYF4 shells, and the obtained products are non-uniform in size. As a result, the UC emission intensity of the complete core-shell NCs increases by about 30 times in comparison with that of the cores, owing to the effective surface passivation of the Ca(2+)-doped cores and therefore protection of Er(3+) in the cores from the non-radiative decay caused by surface defects, whereas the UC intensity of the incomplete core-shell NCs is enhanced by only 3 times.

  15. Physical and optical properties of lithium borosilicate glasses doped with Dy3+ ions

    NASA Astrophysics Data System (ADS)

    Ramteke, D. D.; Gedam, R. S.; Swart, H. C.

    2018-04-01

    The borosilicate glasses with Dy3+ ions were prepared by the melt quench technique with varying concentration of Dy2O3. The glasses were characterized by the density calculation, absorbance and photoluminescence (PL) spectroscopy measurements. Density and molar volume of the glasses increases with increase in Dy3+ ions in the glass matrix. This behavior is correlated with the higher molecular weight and larger ionic radius of Dy3+ ion compared to the other constituents of glass matrix. Emission of Dy3+ doped glasses showed three bands at 482, 573 and at 665 nm which correspond to 6H15/2 (blue), 6H13/2 (yellow) and 6H11/2 (red) transitions. The emission spectra of glasses with different concentration of Dy3+ ions shows that, glasses with 0.5 mol% of Dy2O3 shows highest emission and decreases with further doping. CIE 1931 chromaticity diagram showed that the emission of these glasses was in the white region. Photographs of these glasses under 349 nm Light emitting diode excitation also confirmed the white light emission from these glasses.

  16. Nb-doped rutile TiO₂: a potential anode material for Na-ion battery.

    PubMed

    Usui, Hiroyuki; Yoshioka, Sho; Wasada, Kuniaki; Shimizu, Masahiro; Sakaguchi, Hiroki

    2015-04-01

    The electrochemical properties of the rutile-type TiO2 and Nb-doped TiO2 were investigated for the first time as Na-ion battery anodes. Ti(1-x)Nb(x)O2 thick-film electrodes without a binder and a conductive additive were prepared using a sol-gel method followed by a gas-deposition method. The TiO2 electrode showed reversible reactions of Na insertion/extraction accompanied by expansion/contraction of the TiO2 lattice. Among the Ti(1-x)Nb(x)O2 electrodes with x = 0-0.18, the Ti(0.94)Nb(0.06)O2 electrode exhibited the best cycling performance, with a reversible capacity of 160 mA h g(-1) at the 50th cycle. As the Li-ion battery anode, this electrode also attained an excellent rate capability, with a capacity of 120 mA h g(-1) even at the high current density of 16.75 A g(-1) (50C). The improvements in the performances are attributed to a 3 orders of magnitude higher electronic conductivity of Ti(0.94)Nb(0.06)O2 compared to that of TiO2. This offers the possibility of Nb-doped rutile TiO2 as a Na-ion battery anode as well as a Li-ion battery anode.

  17. Spectroscopic investigation of zinc tellurite glasses doped with Yb(3+) and Er(3+) ions.

    PubMed

    Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

    2016-08-05

    This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80-x-y) TeO2+(0.20) ZnO+xEr2O3+yYb2O3 (x=0, y=0; x=0.004, y=0; x=0, y=0.05 and x=0.004, y=0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er(3+) glasses as erbium doped fiber amplifiers at 1.55μm in infrared emission region. Copyright © 2016 Elsevier B.V. All rights reserved.

  18. Spectroscopic investigation of zinc tellurite glasses doped with Yb3 + and Er3 + ions

    NASA Astrophysics Data System (ADS)

    Bilir, Gökhan; Kaya, Ayfer; Cinkaya, Hatun; Eryürek, Gönül

    2016-08-01

    This paper presents a detailed spectroscopic investigation of zinc tellurite glasses with the compositions (0.80 - x - y) TeO2 + (0.20) ZnO + xEr2O3 + yYb2O3 (x = 0, y = 0; x = 0.004, y = 0; x = 0, y = 0.05 and x = 0.004, y = 0.05 per moles). The samples were synthesized by the conventional melt quenching method. The optical absorption and emission measurements were conducted at room temperature to determine the spectral properties of lanthanides doped zinc tellurite glasses and, to study the energy transfer processes between dopant lanthanide ions. The band gap energies for both direct and indirect possible transitions and the Urbach energies were measured from the absorption spectra. The absorption spectra of the samples were analyzed by using the Judd-Ofelt approach. The effect of the ytterbium ions on the emission properties of erbium ions was investigated and the energy transfer processes between dopant ions were studied by measuring the up-conversion emission properties of the materials. The color quality parameters of obtained visible up-conversion emission were also determined as well as possibility of using the Er3 + glasses as erbium doped fiber amplifiers at 1.55 μm in infrared emission region.

  19. Ion implantation in group III-nitride semiconductors: a tool for doping and defect studies

    NASA Astrophysics Data System (ADS)

    Zolper, J. C.

    1997-06-01

    Ion implantation is a flexible process technology for introducing an array of doping or compensating impurities into semiconductors. As the crystal quality of the group III-nitride materials continues to improve, ion implantation is playing an enabling role in exploring new dopant species and device structures. In this paper we review the recent developments in ion implantation processing of these materials with a particular emphasis on how this technology has brought new understanding to this materials system. In particular, the use of ion implantation to characterize impurity luminescence, doping, and compensation in III-nitride materials is reviewed. In addition, we address the nature of implantation induced damage in GaN which demonstrates a very strong resistance to amorphization while at the same time forming damage that is not easily removed by thermal annealing. Finally, we review the coupling of implantation with high temperature rapid thermal annealing to better understand the thermal stability of these materials and the redistribution properties of the common dopant (Si, O, Be, Mg, Ca, and Zn).

  20. A Liquid Chromatography Detector for Transition and Rare-Earth Metal Ions Based on a Cupric Ion-Selective Electrode

    DTIC Science & Technology

    1981-05-01

    RARE-EARTH METAL IONS BASED ON A CUPRIC ION-SELECTIVE ELECTRODE By - 4 R. CAMERON DOREY TECHNICAL REPORT FJSRL-TR-81-0005 MAY 1981 Approved for public...FORM . REPORT NUMBER 12. GOVT ACCESSION NO. 3. RECIPIENT’S CATALOG NUMBER FJSRL-TR-81-0005BO CO ENGO 4 . TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD...common anions, including halide ions, is shown, and the advantages and limitations of the system are discussed. II ’ 4 UNCLASSIFIED SECURITY

  1. Phase transition in lithium ammonium sulphate doped with cesium metal ions

    NASA Astrophysics Data System (ADS)

    Gaafar, M.; Kassem, M. E.; Kandil, S. H.

    2000-07-01

    Effects of doped cesium (C s+) metal ions (with different molar ratios n) on the phase transition of lithium ammonium sulphate LiNH 4SO 4 system have been studied by measuring the specific heat Cp( T) of the doped systems in the temperature range from 400 to 480 K. The study shows a peculiar phase transition of the pure system ( n=0) characterized by double distinct peaks, changed to a single sharp and narrow one as a result of the doping process. The measurements exhibit different effects of enhanced molar ratios of dopants on the phase transition behaviour of this system. At low dopant content ( n≤3%), the excess specific heat (Δ Cp) max at the transition temperature T1 decreases till a minimum value at n=0.8%, then it increases gradually. In this case, Δ Cp( T) behaviour is varied quantitatively and not modified. Enhanced dopant content ( n>3%) has a pronounced effect on the critical behaviour, which is significantly changed and considerably modified relative to the pure system. In addition, broadening of the critical temperature region, and decrease of (Δ Cp) max associated with changes of the Landau expansion coefficients are obtained and discussed. The study deals with the contribution of the thermally excited dipoles to the specific heat in the ferroelectric region and shows that their energy depends on doping.

  2. Formation of a highly doped ultra-thin amorphous carbon layer by ion bombardment of graphene.

    PubMed

    Michałowski, Paweł Piotr; Pasternak, Iwona; Ciepielewski, Paweł; Guinea, Francisco; Strupiński, Włodek

    2018-07-27

    Ion bombardment of graphene leads to the formation of defects which may be used to tune properties of the graphene based devices. In this work, however, we present that the presence of the graphene layer on a surface of a sample has a significant impact on the ion bombardment process: broken sp 2 bonds react with the incoming ions and trap them close to the surface of the sample, preventing a standard ion implantation. For an ion bombardment with a low impact energy and significant dose (in the range of 10 14 atoms cm -2 ) an amorphization of the graphene layer is observed but at the same time, most of the incoming ions do not penetrate the sample but stop at the surface, thus forming a highly doped ultra-thin amorphous carbon layer. The effect may be used to create thin layers containing desired atoms if no other technique is available. This approach is particularly useful for secondary ion mass spectrometry where a high concentration of Cs at the surface of a sample significantly enhances the negative ionization probability, allowing it to reach better detection limits.

  3. Formation of a highly doped ultra-thin amorphous carbon layer by ion bombardment of graphene

    NASA Astrophysics Data System (ADS)

    Piotr Michałowski, Paweł; Pasternak, Iwona; Ciepielewski, Paweł; Guinea, Francisco; Strupiński, Włodek

    2018-07-01

    Ion bombardment of graphene leads to the formation of defects which may be used to tune properties of the graphene based devices. In this work, however, we present that the presence of the graphene layer on a surface of a sample has a significant impact on the ion bombardment process: broken sp2 bonds react with the incoming ions and trap them close to the surface of the sample, preventing a standard ion implantation. For an ion bombardment with a low impact energy and significant dose (in the range of 1014 atoms cm‑2) an amorphization of the graphene layer is observed but at the same time, most of the incoming ions do not penetrate the sample but stop at the surface, thus forming a highly doped ultra-thin amorphous carbon layer. The effect may be used to create thin layers containing desired atoms if no other technique is available. This approach is particularly useful for secondary ion mass spectrometry where a high concentration of Cs at the surface of a sample significantly enhances the negative ionization probability, allowing it to reach better detection limits.

  4. Detection of singly ionized energetic lunar pick-up ions upstream of earth's bow shock

    NASA Technical Reports Server (NTRS)

    Hilchenbach, M.; Hovestadt, D.; Klecker, B.; Moebius, E.

    1992-01-01

    Singly ionized suprathermal ions upstream of the earth's bow shock have been detected by using the time-of-flight spectrometer SULEICA on the AMPTE/IRM satellite. The data were collected between August and December 1985. The flux of the ions in the mass range between 23 and 37 amu is highly anisotropic towards the earth. The ions are observed with a period of about 29 days around new moon (+/- 3 days). The correlation of the energy of the ions with the solar wind speed and the interplanetary magnetic field orientation indicates the relation to the pick-up process. We conclude that the source of these pick-up ions is the moon. We argue that due to the impinging solar wind, atoms are sputtered off the lunar surface, ionized in the sputtering process or by ensuing photoionization and picked up by the solar wind.

  5. Low-cost plasma immersion ion implantation doping for Interdigitated back passivated contact (IBPC) solar cells

    DOE PAGES

    Young, David L.; Nemeth, William; LaSalvia, Vincenzo; ...

    2016-06-01

    Here, we present progress to develop low-cost interdigitated back contact solar cells with pc-Si/SiO 2/c-Si passivated contacts formed by plasma immersion ion implantation (PIII). PIII is a lower-cost implantation technique than traditional beam line implantation due to its simpler design, lower operating costs, and ability to run high doses (1E14-1E18 cm -2) at low ion energies (20 eV-10 keV). These benefits make PIII ideal for high throughput production of patterned passivated contacts, where high-dose, low-energy implantations are made into thin (20-200 nm) a-Si layers instead of into the wafer itself. For this work symmetric passivated contact test structures (~100 nmmore » thick) grown on n-Cz wafers with pH3 PIII doping gave implied open circuit voltage (iV oc) values of 730 mV with J o values of 2 fA/cm 2. Samples doped with B 2H 6 gave iV oc values of 690 mV and J o values of 24 fA/cm 2, outperforming BF 3 doping, which gave iV oc values in the 660-680 mV range. Samples were further characterized by SIMS, photoluminescence, TEM, EELS, and post-metallization TLM to reveal micro- and macro-scopic structural, chemical and electrical information.« less

  6. Simultaneous Perforation and Doping of Si Nanoparticles for Lithium-Ion Battery Anode.

    PubMed

    Lv, Guangxin; Zhu, Bin; Li, Xiuqiang; Chen, Chuanlu; Li, Jinlei; Jin, Yan; Hu, Xiaozhen; Zhu, Jia

    2017-12-27

    Silicon nanostructures have served as promising building blocks for various applications, such as lithium-ion batteries, thermoelectrics, and solar energy conversions. Particularly, control of porosity and doping is critical for fine-tuning the mechanical, optical, and electrical properties of these silicon nanostructures. However, perforation and doping are usually separated processes, both of which are complicated and expensive. Here, we demonstrate that the porous nano-Si particles with controllable dopant can be massively produced through a facile and scalable method, combining ball-milling and acid-etching. Nano-Si with porosity as high as 45.8% can be achieved with 9 orders of magnitude of conductivity changes compared to intrinsic silicon. As an example for demonstration, the obtained nano-Si particles with 45.8% porosity and 3.7 atom % doping can serve as a promising anode for lithium-ion batteries with 2000 mA h/g retained over 100 cycles at the current density of 0.5 C, excellent rate performance with 1600 mA h/g at the current density of 5 C, and a stable cycling performance of above 1500 mA h/g retained over 940 cycles at the current density of 1 C with carbon coating.

  7. Structural and optical properties of rare earth-doped (Ba{sub 0.77}Ca{sub 0.23}){sub 1-x}(Sm, Nd, Pr, Yb){sub x}TiO{sub 3}

    SciT

    Moraes, A. P. A.; Universidade Federal do Mato Grosso, 78060-900, Araguaia-MT; Filho, A. G. Souza

    2011-06-15

    The structural, dielectric, and vibrational properties of pure and rare earth (RE)-doped Ba{sub 0.77}Ca{sub 0.23}TiO{sub 3} (BCT23; RE = Nd, Sm, Pr, Yb) ceramics obtained via solid-state reaction were investigated. The pure and RE-doped BCT23 ceramics sintered at 1450 deg. C in air for 4 h showed a dense microstructure in all ceramics. The use of RE ions as dopants introduced lattice-parameter changes that manifested in the reduction of the volume of the unit cell. RE-doped BCT23 samples exhibit a more homogenous microstructure due to the absence of a Ti-rich phase in the grain boundaries as demonstrated by scanning electronmore » microscopy imaging. The incorporation of REs led to perturbations of the local symmetry of TiO{sub 6} octahedra and the creation of a new Raman mode. The results of Raman scattering measurements indicated that the Curie temperature of the ferroelectric phase transition depends on the RE ion and ion content, with the Curie temperature shifting toward lower values as the RE content increases, with the exception of Yb{sup 3+} doping, which did not affect the ferroelectric phase transition temperature. The phase transition behavior is explained using the standard soft mode model. Electronic paramagnetic resonance measurements showed the existence of Ti vacancies in the structure of RE-doped BCT23. Defects are created via charge compensation mechanisms due to the incorporation of elements with a different valence state relative to the ions of the pure BCT23 host. It is concluded that the Ti vacancies are responsible for the activation of the Raman mode at 840 cm{sup -1}, which is in agreement with lattice dynamics calculations.« less

  8. Hydrogels dispersed by doped rare earth fluoride nanocrystals: ionic liquid dispersion and down/up-conversion luminescence.

    PubMed

    Yan, Zhi-Yuan; Jia, Li-Ping; Yan, Bing

    2014-01-01

    Two typical kinds of rare earth fluoride nanocrystals codoped with rare earth ions (Eu(3+) and Tm(3+)/Er(3+),Yb(3+)) are synthesized and dispersed in ionic liquid compound (1-chlorohexane-3-methylimidazolium chloride, abbreviated as [C6mim][Cl]). Assisted by agarose, the luminescent hydrogels are prepared homogeneously. The down/up-conversion luminescence of these hydrogels can be realized for the dispersed rare earth fluoride nanocrystals. The results provide a strategy to prepare luminescent (especially up-conversion luminescent) hydrogels with ionic liquid to disperse rare earth fluoride nanocrystals. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. n-type conversion of SnS by isovalent ion substitution: Geometrical doping as a new doping route

    PubMed Central

    Ran, Fan-Yong; Xiao, Zewen; Toda, Yoshitake; Hiramatsu, Hidenori; Hosono, Hideo; Kamiya, Toshio

    2015-01-01

    Tin monosulfide (SnS) is a naturally p-type semiconductor with a layered crystal structure, but no reliable n-type SnS has been obtained by conventional aliovalent ion substitution. In this work, carrier polarity conversion to n-type was achieved by isovalent ion substitution for polycrystalline SnS thin films on glass substrates. Substituting Pb2+ for Sn2+ converted the majority carrier from hole to electron, and the free electron density ranged from 1012 to 1015 cm−3 with the largest electron mobility of 7.0 cm2/(Vs). The n-type conduction was confirmed further by the position of the Fermi level (EF) based on photoemission spectroscopy and electrical characteristics of pn heterojunctions. Density functional theory calculations reveal that the Pb substitution invokes a geometrical size effect that enlarges the interlayer distance and subsequently reduces the formation energies of Sn and Pb interstitials, which results in the electron doping. PMID:26020855

  10. Spectrofluorimetric assessment of hydrochlorothiazide using optical sensor nano-composite terbium ion doped in sol-gel matrix.

    PubMed

    Youssef, A O

    2012-05-01

    A new, simple, sensitive and selective spectrofluorimetric method for the determination of Hydrochlorothiazide was developed in acetonitrile at pH 6.2. The Hydrochlorothiazide can remarkably enhance the luminescence intensity of the Tb(3+) ion doped in sol-gel matrix at λ(ex) = 370 nm. The intensity of the emission band of Tb(3+) ion doped in sol-gel matrix was increased due to the energy transfer from the triplet excited state of Hydrochlorothiazide to ((5)D(4)) excited energy state of Tb(3) ion. The enhancement of the emission band of Tb(3+) ion doped in sol-gel matrix at ((5)D(4)→(7)F(5)) 545 nm was directly proportion to the concentration of Hydrochlorothiazide with a dynamic ranges of 5.0 × 10(-10)-5.0 × 10(-6) mol L(-1) and detection limit of 2.2 × 10(-11) mol L(-1).

  11. Gamma rays shielding and sensing application of some rare earth doped lead-alumino-phosphate glasses

    NASA Astrophysics Data System (ADS)

    Kaur, Preet; Singh, Devinder; Singh, Tejbir

    2018-03-01

    Seven rare earth (Sm3+, Eu3+ and Nd3+) doped lead alumino phosphate glasses were prepared. The protective and sensing measures from gamma rays were analysed in terms of parameters viz. density (ρ), refractive index, energy band gap (Eg), mean free path (mfp), effective atomic number (Zeff) and buildup factors (energy absorption EABF as well as exposure buildup factor EBF). The energy dependent parameters (mfp, Zeff, EABF and EBF) were investigated in the energy region from 15 keV to 15 MeV. EABF and EBF values were observed to be maximum in the intermediate energy region. Besides, the EABF and EBF values for the prepared samples are shown to have strong dependence on chemical composition of the glass at lower energy, whereas, it is almost independent of chemical composition in higher energy region. The prepared glass samples are found to have potential applications in radiation shielding as well as radiation sensing, which further find numerous applications in the field of medicine and industry.

  12. Rare-earth-doped nanophosphors for multicolor cathodoluminescence nanobioimaging using scanning transmission electron microscopy.

    PubMed

    Furukawa, Taichi; Fukushima, Shoichiro; Niioka, Hirohiko; Yamamoto, Naoki; Miyake, Jun; Araki, Tsutomu; Hashimoto, Mamoru

    2015-05-01

    We describe rare-earth-doped nanophosphors (RE-NPs) for biological imaging using cathodoluminescence(CL) microscopy based on scanning transmission electron microscopy (STEM). We report the first demonstration of multicolor CL nanobioimaging using STEM with nanophosphors. The CL spectra of the synthesized nanophosphors (Y2O3∶Eu, Y2O3∶Tb) were sufficiently narrow to be distinguished. From CL images of RE-NPs on an elastic carbon-coated copper grid, the spatial resolution was beyond the diffraction limit of light.Y2O3∶Tb and Y2O3∶Eu RE-NPs showed a remarkable resistance against electron beam exposure even at high acceleration voltage (80 kV) and retained a CL intensity of more than 97% compared with the initial intensity for 1 min. In biological CL imaging with STEM, heavy-metal-stained cell sections containing the RE-NPs were prepared,and both the CL images of RE-NPs and cellular structures, such as mitochondria, were clearly observed from STEM images with high contrast. The cellular CL imaging using RE-NPs also had high spatial resolution even though heavy-metal-stained cells are normally regarded as highly scattering media. Moreover, since theRE-NPs exhibit photoluminescence (PL) excited by UV light, they are useful for multimodal correlative imaging using CL and PL.

  13. Emission properties of Ce-doped alkaline earth borate glasses for scintillator applications

    NASA Astrophysics Data System (ADS)

    Torimoto, Aya; Masai, Hirokazu; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

    2017-11-01

    We investigate the photoluminescence (PL) and X-ray-induced luminescence properties of 0.1 mol% Ce-doped MO-B2O3 (M = Ca, Sr, and Ba) glasses. We also determine the Ce3+/(Ce3++Ce4+) ratio by X-ray absorption near-edge structure analyses. The emission intensities of PL, X-ray scintillation, and thermally stimulated luminescence (TSL) depend on the host glass composition. The order of the PL intensity from highest to lowest is as follows: Ca-substituted glass, Ba-substituted glass, and Sr-substituted glass. Our results suggest that the optical absorption edge and quantum yield (QY) are influenced by the local coordination state of Ce3+, which, in turn, is likely to be affected by the optical basicity. The order of the X-ray scintillation intensity from highest to lowest is reverse of that of the PL intensity. This is probably because the interaction probability of X-rays with matter depends on the effective atomic number of the material and the effective atomic number has a stronger influence on the scintillation intensity than does the QY. Though the TSL glow curves reveal that the density and energy depth of the trap sites depend on the substituted alkaline earth oxides, we are unable to correlate the electron spin resonance (ESR) spectra with the TSL results. Therefore, it is considered that the ESR active sites are not responsible for the TSL in these systems.

  14. Microstructure and spectroscopic investigations of calcium zinc bismuth phosphate glass ceramics doped with manganese ions

    NASA Astrophysics Data System (ADS)

    Suneel Kumar, A.; Sambasiva Rao, M. V.; Chinna Ram, G.; Krishna Rao, D.

    2018-01-01

    Multi-component 10CaF2-20ZnO-(15 - x)Bi2O3-55P2O5:xMnO (0 ≤ x ≤ 2.5) glass ceramics were synthesised by melt quenching technique and heat treatment. The prepared glass ceramics were characterised by XRD, DTA, EDS and SEM. Spectroscopic studies such as optical absorption, EPR, FTIR and Raman were also carried out on these glass ceramics. The XRD and SEM studies have indicated that ceramic samples contain well defined and randomly distributed grains of different crystalline phases. The observed increase of enthalpy from DTA patterns up to 1 mol% of MnO indicates that the crystallisation starts initially from the surface of the material then gradually it is extended to the volume of the material and this influence is meagre at higher concentrations of MnO. The absorption spectra of manganese doped glass ceramics have exhibited two types of conventional bands; one due to Mn2+ ions and other due to Mn3+ ions. The EPR spectra of MnO doped glass ceramics showed a resonance signal around g2 = 2.023 with a six line hyperfine structure and another signal at about g1 = 4.314. The relative intensity and half-width of these two signals are observed to increase with the increase in the concentration of manganese ions up to 1 mol% beyond this concentration it is found to decrease. Such observation indicates the conversion of part of Mn2+ ions into Mn3+ ions in the glass ceramic matrix. The observed increase in the intensity of symmetrical structural units at the expense of asymmetrical structural units from the FTIR and Raman spectra at higher concentration of MnO indicating that Mn2+ ions occupy the network forming positions in the glass ceramic structure.

  15. First-principles prediction of Si-doped Fe carbide as one of the possible constituents of Earth's inner core

    NASA Astrophysics Data System (ADS)

    Das, Tilak; Chatterjee, Swastika; Ghosh, Sujoy; Saha-Dasgupta, Tanusri

    2017-09-01

    We perform a computational study based on first-principles calculations to investigate the relative stability and elastic properties of the doped and undoped Fe carbide compounds at 200-364 GPa. We find that upon doping a few weight percent of Si impurities at the carbon sites in Fe7C3 carbide phases, the values of Poisson's ratio and density increase while VP, and VS decrease compared to their undoped counterparts. This leads to marked improvement in the agreement of seismic parameters such as P wave and S wave velocity, Poisson's ratio, and density with the Preliminary Reference Earth Model (PREM) data. The agreement with PREM data is found to be better for the orthorhombic phase of iron carbide (o-Fe7C3) compared to hexagonal phase (h-Fe7C3). Our theoretical analysis indicates that Fe carbide containing Si impurities can be a possible constituent of the Earth's inner core. Since the density of undoped Fe7C3 is low compared to that of inner core, as discussed in a recent theoretical study, our proposal of Si-doped Fe7C3 can provide an alternative solution as an important component of the Earth's inner core.

  16. Doped δ-bismuth oxides to investigate oxygen ion transport as a metric for condensed phase thermite ignition.

    PubMed

    Wang, Xizheng; Zhou, Wenbo; DeLisio, Jeffery B; Egan, Garth C; Zachariah, Michael R

    2017-05-24

    Nanothermites offer high energy density and high burn rates, but are mechanistically only now being understood. One question of interest is how initiation occurs and how the ignition temperature is related to microscopic controlling parameters. In this study, we explored the potential role of oxygen ion transport in Bi 2 O 3 as a controlling mechanism for condensed phase ignition reaction. Seven different doped δ-Bi 2 O 3 were synthesized by aerosol spray pyrolysis. The ignition temperatures of Al/doped Bi 2 O 3 , C/doped Bi 2 O 3 and Ta/doped Bi 2 O 3 were measured by temperature-jump/time-of-flight mass spectrometer coupled with a high-speed camera respectively. These results were then correlated to the corresponding oxygen ion conductivity (directly proportional to ion diffusivity) for these doped Bi 2 O 3 measured by impedance spectroscopy. We find that ignition of thermite with doped Bi 2 O 3 as oxidizer occurs at a critical oxygen ion conductivity (∼0.06 S cm -1 ) of doped Bi 2 O 3 in the condensed-phase so long as the aluminum is in a molten state. These results suggest that oxygen ion transport limits the condensed state Bi 2 O 3 oxidized thermite ignition. We also find that the larger oxygen vacancy concentration and the smaller metal-oxide bond energy in doped Bi 2 O 3 , the lower the ignition temperature. The latter suggests that we can consider the possibility of manipulating microscopic properties within a crystal, to tune the resultant energetic properties.

  17. Porous nitrogen-doped carbon microspheres as anode materials for lithium ion batteries.

    PubMed

    Chen, Taiqiang; Pan, Likun; Loh, T A J; Chua, D H C; Yao, Yefeng; Chen, Qun; Li, Dongsheng; Qin, Wei; Sun, Zhuo

    2014-10-28

    Nitrogen-doped carbon microspheres (NCSs) were fabricated via a simple, fast and energy-saving microwave-assisted method followed by thermal treatment under an ammonia atmosphere. NCSs thermally treated at different temperatures were investigated as anode materials for lithium ion batteries (LIBs). The results show that NCSs treated at 900 °C exhibit a maximum reversible capacity of 816 mA h g(-1) at a current density of 50 mA g(-1) and preserve a capacity of 660 mA h g(-1) after 50 cycles, and even at a high current density of 1000 mA g(-1), a capacity of 255 mA h g(-1) is maintained. The excellent electrochemical performance of NCSs is due to their porous structure and nitrogen-doping. The present NCSs should be promising low-cost anode materials with a high capacity and good cycle stability for LIBs.

  18. Superior Cathode Performance of Nitrogen-Doped Graphene Frameworks for Lithium Ion Batteries.

    PubMed

    Xiong, Dongbin; Li, Xifei; Bai, Zhimin; Shan, Hui; Fan, Linlin; Wu, Chunxia; Li, Dejun; Lu, Shigang

    2017-03-29

    Development of alternative cathode materials is of highly desirable for sustainable and cost-efficient lithium-ion batteries (LIBs) in energy storage fields. In this study, for the first time, we report tunable nitrogen-doped graphene with active functional groups for cathode utilization of LIBs. When employed as cathode materials, the functionalized graphene frameworks with a nitrogen content of 9.26 at% retain a reversible capacity of 344 mAh g -1 after 200 cycles at a current density of 50 mA g -1 . More surprisingly, when conducted at a high current density of 1 A g -1 , this cathode delivers a high reversible capacity of 146 mAh g -1 after 1000 cycles. Our current research demonstrates the effective significance of nitrogen doping on enhancing cathode performance of functionalized graphene for LIBs.

  19. Energization of Ions in near-Earth current sheet disruptions

    NASA Technical Reports Server (NTRS)

    Taktakishvili, A.; Lopez, R. E.; Goodrich, C. C.

    1995-01-01

    In this study we examine observations made by AMPTE/CCE of energetic ion bursts during seven substorm periods when the satellite was located near the neutral sheet, and CCE observed the disruption cross-tail current in situ. We compare ion observations to analytic calculations of particle acceleration. We find that the acceleration region size, which we assume to be essentially the current disruption region, to be on the order of 1 R(sub E). Events exhibiting weak acceleration had either relatively small acceleration regions (apparently associated with pseudobreakup activity on the ground) or relatively small changes in the local magnetic field (suggesting that the magnitude of the local current disruption region was limited). These results add additional support for the view that the particle bursts observed during turbulent current sheet disruptions are due to inductive acceleration of ions.

  20. Tunable optical properties of some rare earth elements-doped mayenite Ca12Al14O33 nanopowders elaborated by oxalate precursor route

    NASA Astrophysics Data System (ADS)

    Rashad, Mohamed M.; Mostafa, Ahmed G.; Mwakikunga, Bonex W.; Rayan, Diaa A.

    2017-01-01

    Rare earth (RE) ions-doped mayenite Ca12Al14- x RE x O33 nanopowders (where RE = La and Gd and x = 0-1.0) were synthesized using the oxalate precursor technique. The as-prepared precursors were calcined at 800 °C for 2 h. Obviously, all RE-doped Ca12Al14- x RE x O33 possessed a well-crystalline cubic mayenite phase till RE content of 0.8. The crystallo-chemical aspects including crystallite size, lattice parameters, theoretical X-ray density and bulk density were robustly on RE nature and ratio. The microstructure and the average grain size were significantly influenced by the RE kind and content. The high transparency of Ca12Al14- x RE x O33 over 80% was found to be evinced in the visible wavelength range of 400-800 nm. Besides, the incorporation of RE cation minimized the direct band gap energy from 4.42 eV for pure mayenite to 3.85 and 3.59 eV with x value 1.0 of La3+ and Gd3+ ions. The photoluminescence spectra of pure mayenite nanoparticles showed that the band edge emission ( λ exc = 248 nm) with an intense visible emission band at 360 nm was detected. Otherwise, the band edge emission showed a slight shift toward short wavelength due to the substitution Al3+ by RE3+ ions. Such results open a new avenue for application of mayenite as a good candidate for transparent low-temperature electron conductor for optoelectronics applications.

  1. Solar forcing, and ionospheric ion outflow from Venus, Earth and Mars - A comparison

    NASA Astrophysics Data System (ADS)

    Lundin, R. N.

    2012-12-01

    Solar forcing by e.g. EUV radiation and the solar wind leads to outflow and escape of ionospheric ions from Earth, Venus and Mars. In-situ measurements in the Earth's space environment have demonstrated that the ion escape rate correlates with the magnitude of solar forcing, i.e. high solar EUV and solar wind forcing leads to enhanced escape rates. The Terrestrial outflow is dominated by H+ and O+ suggesting that the ultimate origin of outflowing ions is water. Recent measurements from the two arid planets Mars and Venus, their atmospheres dominated by CO2, display characteristics similar to that of the Earth - an outflow dominated by hydrogen (H+) and oxygen (O+, O2+) ions. Despite major differences in atmospheric composition, the composition of the ion outflow from Earth and Venus is very similar, i.e. H+ and O+ dominates and the outflow has a stoichiometric H/O ratio of close to 2. The latter implies escape of water. The ion outflow from Mars is dominated by O+, O2+, and H+. Here the stoichiometric ratio between hydrogen and oxygen ion is ≈1, implying that if the ion outflow originates from water, about half of the hydrogen mass disappears by other means. The primary origin of the ion outflow from Earth, Venus and Mars is a complex issue. Nevertheless, a predominant hydrogen and oxygen loss implies that water can easily escape planets orbiting close to the Sun, while Carbon-based molecules (e.g. CO2) resides more easily. Observations shows that the outflow of e.g. CO+ and CO2+ from Mars and Venus is minute compared to the outflow of hydrogen and oxygen ions. Magnetic shielding is an issue affecting the net ion outflow and escape from a planet, because acceleration processes are also the characteristics of magnetized plasmas. Recent findings suggests that, despite magnetic field pile-up at Mars and Venus, the stand-off distance is insufficient to prohibit a direct interaction between the solar wind and the magnetized ionospheric plasma in the induced

  2. Synthesis and Characterization Materials M-Barium Hexaferrite Doping Ions Co-Mn Nano Particle

    NASA Astrophysics Data System (ADS)

    Susilawati; Doyan, A.; Sahlam

    2017-05-01

    This research has been success in the synthesis of M-Barium hexaferrite (BaM) doping Co-Mn ions using coprecipitation method are expected to be applied as a base material in the coating RADAR. M-Barium hexaferrite (BaM) are BaFe12-2xCoxMnxO19 synthesized with various concentrations (x = 0.0, 0.1, 0.2, 0.3) and the calcinations temperature (T = 400°C, 600°C, 800°C). The materials characterization using a X-Ray Diffraction (XRD), Transmission Electron Microscope (TEM), Inductance Capacitance and resistance (LCR) meter, and Vibrating Sample Magnetometer (VSM) Instruments. The measurement results using XRD shows the material has a hexagonal crystalline structure. The measurement results using a TEM show a sample of nano crystal materials with grain diameters up to 40 nm and spacing of the crystal lattice. The measurement results using a LCR-meter shows the electric conductivity of 1.15 × 10-6 S/cm to BaM without doping, 3.75 × 10-6 S/cm to 0.1 doping concentration calcination temperature of 400 °C, and 1,23 × 10-5 S/cm to 0.3 doping concentration calcination temperature of 800 °C, thus including semiconductor materials. The magnetic properties of materials using a VSM test results show the value of coercivity of 0.1 T; remanence value of 0.06 emu/g; and the saturation value of 0.42 emu/g. The results above show BaM Co-Mn metal doping potential as anti-radar material.

  3. Effect of rare-earth doping on the thermoelectric and electrical transport properties of the transition metal pentatelluride hafnium pentatelluride

    NASA Astrophysics Data System (ADS)

    Lowhorn, Nathan Dane

    The transition metal pentatellurides HfTe5 and ZrTe5 have been observed to possess interesting electrical transport properties. High thermopower and low resistivity values result in high thermoelectric power factors. In addition, they possess anomalous transport behavior. The temperature dependence of the resistivity is semimetallic except for a large resistive peak as a function of temperature at around 75 K for HfTe5 and 145 K for ZrTe5. At a temperature corresponding to this peak, the thermopower crosses zero as it moves from large positive values to large negative values. This behavior has been found to be extremely sensitive to changes in the energetics of the system through influences such as magnetic field, stress, pressure, microwave radiation, and substitutional doping. This behavior has yet to be fully explained. Previous doping studies have shown profound and varied effects on the anomalous transport behavior. In this study we investigate the effect on the electrical resistivity, thermopower, and magnetoresistance of doping HfTe5 with rare-earth elements. We have grown single crystals of nominal Hf0.75RE 0.25Te5 where RE = Ce, Pr, Nd, Sm, Gd, Tb, Dy, and Ho. Electrical resistivity and thermopower data from about 10 K to room temperature are presented and discussed in terms of the thermoelectric properties. Doping with rare-earth elements of increasing atomic number leads to a systematic suppression of the anomalous transport behavior. Rare-earth doping also leads to an enhancement of the thermoelectric power factor over that of previously studied pentatellurides and the commonly used thermoelectric material Bi2Te3. For nominal Hf0.75Nd0.25Te5 and Hf0.75 Sm0.25Te5, values more than a factor of 2 larger than that Bi2Te3 are observed. In addition, suppression of the anomalous transport behavior leads to a suppression of the large magnetoresistive effect observed in the parent compounds. Rare-earth doping of HfTe5 has a profound impact on the anomalous

  4. Structural and optical study on antimony-silicate glasses doped with thulium ions.

    PubMed

    Dorosz, D; Zmojda, J; Kochanowicz, M; Miluski, P; Jelen, P; Sitarz, M

    2015-01-05

    Structural, spectroscopic and thermal properties of SiO₂-Al₂O₃-Sb₂O₃-Na₂O glass system doped with 0.2 mol% Tm₂O₃ have been presented. Synthesis of antimony-silicate glasses with relatively low phonon energy (600 cm(-1), which implicates a small non-radiative decay rate) was performed by conventional high-temperature melt-quenching methods. The effect of SiO₂/Sb₂O₃ ratio in fabricated Tm(3+) doped glass on thermal, structural and luminescence properties was investigated. On the basis of structural investigations decomposition of absorption bands in the infrared FTIR region was performed, thus determining that antimony ions are the only glass-forming ions, setting up the lattice of fabricated glasses. Luminescence band at the wavelength of 1.8 μm corresponding to (3)F₄→(3)H₆ transition in thulium ions was obtained under 795 nm laser pumping. It was observed that combination of relatively low phonon energy and greater separation of optically active centers in the fabricated glasses influenced in decreasing the luminescence intensity at 1800 nm. Copyright © 2014 Elsevier B.V. All rights reserved.

  5. Theoretical study of room temperature ferromagnetism and band gap energy of pure and ion doped In2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Apostolov, A. T.; Apostolova, I. N.; Wesselinowa, J. M.

    2018-06-01

    Using the s-d microscopic model including the electron-phonon interaction and the Green's function theory we have considered the origin of room temperature ferromagnetism (RTFM) in pure and ion doped In2O3 nanoparticles (NPs). The magnetization M increases with decreasing particle size. M of Fe, Tb and Mn doped In2O3 NPs is investigated, which increases, decreases and has a maximum, respectively, with increasing doping concentration. The RTFM is due to surface oxygen vacancies and different ionic radius of the dopants compared to that of the host ions. This differences lead to different strains which changes the exchange interaction constants. We have calculated the dependence of the band gap energy on the particle size in In2O3 NPs and the Fe concentration of Fe doped In2O3 NPs. The results are in good qualitative agreement with the experimental data.

  6. Investigations on the spectroscopic properties of Dy3 + ions doped Zinc calcium tellurofluoroborate glasses

    NASA Astrophysics Data System (ADS)

    Karthikeyan, P.; Arunkumar, S.; Annapoorani, K.; Marimuthu, K.

    2018-03-01

    A new series of Dy3 + doped (30-x)B2O3 + 30TeO2 + 20CaCO3 + 10ZnO + 10ZnF2 + xDy2O3 (x = 0.01, 0.1, 0.5, 1, 2 and 3 in wt%) Zinc calcium tellurofluoroborate glasses were prepared and their structural, luminescence and excited state dynamics have been studied and reported. The structural properties have been characterized through XRD and FTIR studies to confirm the amorphous nature and to explore the presence of fundamental stretching vibrations. The bonding parameters (δ and β), optical band gap, Urbach's energy, oscillator strengths and Judd-Ofelt (JO) intensity parameters were calculated from the absorption spectra. The JO intensity parameters and the Y/B intensity ratio values have been used to explore the nature of the bonding and asymmetry around the Dy-ligand field environment. The luminescence properties of the present Dy3 + doped glasses have been analyzed through luminescence excited state dynamics and radiative properties such as transition probability (A), stimulated emission cross-section (σPE) branching ratio (β) and radiative lifetime (τR) values. The combination of dominant blue (4F9/2 → 6H15/2) and yellow (4F9/2 → 6H13/2) emissions generates white light emission in the CIE chromaticity diagram thus suggests that the present Dy3 + doped glasses are suitable for white light applications. The lifetime of the 4F9/2 excited state is found to decrease with the increase in Dy3 + ion content and the concentration quenching of the Dy3 + ions emission could be ascribed due to the resonant energy transfer and cross-relaxation processes. The non-exponential behavior of the decay curves has been analyzed with Inokuti-Hirayama model and the interaction between the Dy3 + ions is of electric dipole-dipole in nature.

  7. Ion distributions in the Earth's foreshock upstream from the bow shock

    NASA Technical Reports Server (NTRS)

    Fuselier, S. A.

    1995-01-01

    A variety of suprathermal and energetic ion distributions are found upstream from shocks. Some distributions, such as field-aligned beams, are generated directly at the shock either through reflection processes or through leakage from the hotter downstream region. Other distributions, such as intermediate distributions, evolve from these parent distributions through wave-particle interactions. This paper reviews our current understanding of the creation and evolution of suprathermal distributions at shocks. Examples of suprathermal ion distributions are taken from observations at the Earth's bow shock. Particular emphasis is placed on the creation of field-aligned beams and specularly reflected ion distributions and on the evolution of these distributions in the Earth's ion foreshock. However, the results from this heavily studied region are applicable to interplanetary shocks, bow shocks at other planets, and comets.

  8. A novel approach to prepare optically active ion doped luminescent materials via electron beam evaporation into ionic liquids

    DOE PAGES

    Richter, K.; Lorbeer, C.; Mudring, A. -V.

    2014-11-10

    A novel approach to prepare luminescent materials via electron-beam evaporation into ionic liquids is presented which even allows doping of host lattices with ions that have a strong size mismatch. Thus, to prove this, MgF 2 nanoparticles doped with Eu 3+ were fabricated. The obtained nanoparticles featured an unusually high luminescence lifetime and the obtained material showed a high potential for application.

  9. Effect of Co2+ Ions Doping on the Structural and Optical Properties of Magnesium Aluminate

    NASA Astrophysics Data System (ADS)

    Kanwal, Kiran; Ismail, Bushra; Rajani, K. S.; Kissinger, N. J. Suthan; Zeb, Aurang

    2017-07-01

    Cobalt-doped nanosized magnesium aluminate (Mg1-xCoxAl2O4) samples having different compositions ( x = 0.2, 0.4, 0.6, 0.8, 1.0) were synthesized by a chemical co-precipitation method. All samples were characterized by means of x-ray diffraction (XRD), scanning electron microscopy, Fourier transform infrared spectroscopy, ultra violet-visible spectroscopy, photoluminescence and diffused reflectance spectroscopy. The results of XRD revealed that the samples were spinel single phase cubic close packed crystalline materials. The lattice constant and x-ray density were found to be affected by the ionic radii of the doped metal cations. Using the Debye-Scherrer formula, the calculated crystalline size was found to be Co2+ ion concentration-dependent and varied between 32 nm and 40 nm. Nano-dimensions and phase of the Mg1-xCoxAl2O4 samples were analyzed and the replacement of Mg2+ ions with Co2+ ions was confirmed by elemental analysis. Three strong absorption bands at 540 nm, 580 nm and 630 nm were observed for the doped samples which are attributed to the three spin-allowed 4T1g (4F) → 4T2g, 4A2g, 4T1g (4P) electronic transitions of Co2+ at tetrahedral lattice sites. Nanophosphors have optical properties different from bulk because of spatial confinement and non-radiative relaxation. Decreases in particle size can increase the surface area and the defects, which can in turn increase the luminescent efficiency to make it very useful for tunable laser operations, persistent phosphorescence, color centers, photoconductivity and luminescence for display technology. MgAl2O4 was doped with Co2+ ions using a co-precipitation method and the optical absorption studies revealed that there is a decrease of band gap due to the increase of Co2+ content. The emission intensity of this phosphor is observed at 449 nm with a sharp peak attributed to the smaller size of the particles and the homogeneity of the powder.

  10. Anodic stripping voltammetry of nickel ions and nickel hydroxide nanoparticles at boron-doped diamond electrodes

    NASA Astrophysics Data System (ADS)

    Musyarofah, N. R. R.; Gunlazuardi, J.; Einaga, Y.; Ivandini, T. A.

    2017-04-01

    Anodic stripping voltammetry (ASV) of nickel ions in phosphate buffer solution (PBS) have been investigated at boron-doped diamond (BDD) electrodes. The deposition potential at 0.1 V (vs. Ag/AgCl) for 300 s in 0.1 M PBS pH 3 was found as the optimum condition. The condition was applied for the determination of nickel contained in nickel hydroxide nanoparticles. A linear calibration curve can be achieved of Ni(OH)2-NPs in the concentration range of x to x mM with an estimated limit of detection (LOD) of 5.73 × 10-6 mol/L.

  11. Growth and characterization of divalent transition metal ions doped zinc hydrogen phosphate single crystals

    NASA Astrophysics Data System (ADS)

    D'Souza, Delma; Jagannatha, N.; Nagaraja, K. P.; Rohith, P. S.; Pradeepkumar, K. V.

    2018-05-01

    Zinc hydrogen phosphate (ZnHP) single crystal co-doped with divalent transition metal ions Cobalt (Co2+) and Cadmium (Cd2+) is grown by gel technique in silica hydro gel media. The presence of Co2+ and Cd2+ dopants in the ZnHP crystal was confirmed by Energy Dispersive X-ray Analysis (EDAX).FTIR spectra of the grown crystal depict the stretching and bending vibration of PO4 units, water of crystallization and metal-oxygen bonds. Powder XRD analysis reveals that the grown crystal belongs to monoclinic system with spacegroup P 21. The thermal stability of the grown crystal is rectified from TG-DSC studies.

  12. Microwave-assisted one-pot synthesis of water-soluble rare-earth doped fluoride luminescent nanoparticles with tunable colors

    PubMed Central

    Mi, Cong-Cong; Tian, Zhen-huang; Han, Bao-fu; Mao, Chuan-bin; Xu, Shu-kun

    2012-01-01

    Polyethyleneimine (PEI) functionalized multicolor luminescent LaF3 nanoparticles were synthesized via a novel microwave-assisted method, which can achieve fast and uniform heating under eco-friendly and energy efficient conditions. The as-prepared nanoparticles possess a pure hexagonal structure with an average size of about 12 nm. When doped with different ions (Tb3+ and Eu3+), the morphology and structure of the nanoparticles were not changed, whereas the optical properties varied with doped ions and their molar ratio, and as a result emission of four different colors (green, yellow, orange and red) were achieved by simply switching the types of doping ions (Eu3+ versus Tb3 +) and the molar ratio of the two doping ions. PMID:22879690

  13. Growth, improved thermal stability and spectral properties of Yb3+-ions doped high temperature phase α-Ba3Gd(BO3)3 crystals co-doped by Sr2+, Ca2+ and La3+ ions

    NASA Astrophysics Data System (ADS)

    Pan, Shangke; Zhang, Jianyu; Pan, Jianguo

    2018-02-01

    To investigate the cause of the thermal instability of Yb3+-ions doped Ba3Gd(BO3)3 crystal grown from Czochralski technique, the low temperature phase β-Ba3Gd(BO3)3 powder was synthesized at the temperature of 800 °C. To inhibit the phase transition of high temperature phase Yb:α-Ba3Gd(BO3)3 during the crystal growth process, co-doping ions Sr2+, Ca2+ and La3+ ions were introduced in Yb:α-Ba3Gd(BO3)3 crystal. The melting point increased and the thermal stability of Yb:α-Ba3Gd(BO3)3 crystal was improved by co-doping ions. The absorption peaks of co-doped crystals centered at 976 nm with FWHM of 11, 11 and 12 nm and the absorption cross sections were 3.40 × 10-21 cm2, 4.00 × 10-21 cm2 and 2.66 × 10-21 cm2, respectively. The emission cross sections at 1040 nm were 2.19 × 10-21 cm2, 2.53 × 10-21 cm2 and 1.93 × 10-21 cm2, respectively. The fluorescence times of co-doped by Sr2+, Ca2+ and La3+ ions were shorter than that of Yb:α-Ba3Gd(BO3)3 crystal. So Yb:α-Ba3Gd(BO3)3 crystals co-doped by Sr2+, Ca2+ and La3+ ions will be more suitable for LD-pumping laser.

  14. Ion flow ripples in the Earth's plasma sheet

    NASA Astrophysics Data System (ADS)

    De Spiegeleer, Alexandre; Hamrin, Maria; Pitkänen, Timo; Norqvist, Patrik; Mann, Ingrid

    2016-04-01

    For a long time, magnetotail flows were considered rather smooth and laminar, and primarily dominated by a simple convection flow pattern. However, in the early 90's, high speed bursty bulk flows (BBFs) were discovered and found to commonly perturb the underlying convection flows. In addition, there are other disturbances complicating the magnetotail flow pattern. Instabilities such as the Kelvin-Helmholz instability and the kink instability can cause different types of magnetic field oscillations, such as field line resonances. It is expected that ions will follow these oscillations if the typical time and length scales are larger than the gyroperiod and gyroradius of the ions. Though low-velocity sloshing and ripple disturbances of the average magnetotail convection flows have been observed, their connection with magnetic field oscillations is not fully understood. Furthermore, when studying BFFs, these "Ion Flow Ripples" (IFRs) are often neglected, dismissed as noise or can even erroneously be identified as BBFs. It is therefore of utter importance to find out and understand the role of IFRs in magnetotail dynamics. In a statistical investigation, we use several years of Cluster plasma sheet data to study the low-speed flows in the magnetotail. We investigate different types of IFRs, study their occurrence, and discuss their possible causes.

  15. Investigating the Doping Mechanism of Pyrene Based Methacrylate Functional Conductive Binder in Silicon Anodes for Lithium-Ion Batteries

    DOE PAGES

    Ling, Min; Liu, Michael; Zheng, Tianyue; ...

    2017-01-01

    The doping mechanism of poly (1-pyrenemethyl methacrylate) (PPy) is investigated through electrochemical analytical and spectroscopic method. The performance of PPy as a Si materials binder is studied and compared with that of a commercial available lithium polyacrylate (PAALi) binder. The pyrene moiety consumes lithium ions according to the cyclic voltammogram (CV) measurement, as a doping to the PPy binder. Based on the lithium consumption, PPy based Si/graphite electrode doping is quantified at 1.1 electron/pyrene moiety. Lastly, the PPy binder based electrodes surface are uniform and crack free during lithiation/delithiation, which is revealed through Scanning electron microscope (SEM) imaging.

  16. Observations of nonadiabatic acceleration of ions in Earth's magnetotail

    NASA Technical Reports Server (NTRS)

    Frank, L. A.; Paterson, W. R.; Kivelson, M. G.

    1994-01-01

    We present observations of the three-dimensional velocity distributions of protons in the energy range 20 eV to 52 keV at locations within and near the current sheet of Earth's magnetotail at geocentric radial distances 35 to 87 R(sub E). These measurements were acquired on December 8, 1990, with a set of electrostatic analyzers on board the Galileo spacecraft during its approach to Earth in order to obtain one of its gravitational assists to Jupiter. It is found that the velocity distributions are inadequately described as quasi-Maxwellian distributions such as those found in the central plasma sheet at positions nearer to Earth. Instead the proton velocity distributions can be categorized into two major types. The first type is the 'lima bean' shaped distribution with high-speed bulk flows and high temperatures that are similar to those found nearer to Earth in the plasma sheet boundary layer. The second type consists of colder protons with considerably lesser bulk flow speeds. Examples of velocity distributions are given for the plasma mantle, a region near the magnetic neutral line, positions earthward and tailward of the neutral line, and the plasma sheet boundary layer. At positions near the neutral line, only complex velocity distributions consisting of the colder protons are found, whereas both of the above types of distributions are found in and near the current sheet at earthward and tailward locations. Bulk flows are directed generally earthward and tailward at positions earthward and tailward of the neutral line, respectively. Only the high-speed, hot distribution is present in the plasma sheet boundary layer. The observations are interpreted in terms of the nonadiabatic acceleration of protons that flow into the current sheet from the plasma mantle. For this interpretation the hot, 'lima bean' shaped distributions are associated with meandering, or Speiser, orbits in the current sheet. It is suggested that the colder, lower-speed proton velocity

  17. On the origins of energetic ions in the Earth's dayside magnetosheath

    SciT

    Fuselier, S.A.; Klumpar, D.M.; Shelley, E.G.

    1991-01-01

    Energetic ion events in the Earth's dayside subsolar magnetosheath (0900 - 1300 Local Time) are surveyed using data from the Active Magnetospheric Particle Tracer Explorers/Charge Composition Explorer (AMPTE/CCE) Hot Plasma Composition Experiment. Ion species carrying the signature of their origin (O{sup +} and energetic He{sup 2+}) are used to distinguish between magnetospheric and solar wind orgins for the energetic ion events. The results of this survey indicate that the majority of energetic (10-17 keV/e) H{sup +} and He{sup 2+} ions observed in the dayside magnetosheath are accelerated from the solar wind population. The energetic He{sup 2+} to H{sup +} densitymore » ratio in the magnetosheath is consistent with that predicted from first-order Fermi acceleration of solar wind ions in the turbulent regions upstream and downstream from the Earth's quasi-parallel bow shock. Although the majority of the energetic ions appear to be of solar wind origin, magnetospheric O{sup +} is also occasionally present in the magnetosheath. The simultaneous occurence of both energetic He{sup 2+} and magnetospheric O{sup +} indicates that, on occasion, both Fermi acceleration of solar wind ions and leakage of magnetospheric ions occurs in the dayside magnetosheath.« less

  18. Visible light responsive sulfated rare earth doped TiO(2)@fumed SiO(2) composites with mesoporosity: enhanced photocatalytic activity for methyl orange degradation.

    PubMed

    Zhan, Changchao; Chen, Feng; Yang, Jintao; Dai, Daoxing; Cao, Xiaohua; Zhong, Mingqiang

    2014-02-28

    Visible light (VL) responsive mesoporous sulfated rare earth ions (Nd(3+), La(3+), Y(3+)) incorporated TiO2@fumed SiO2 photocatalysts were prepared by sol-gel method with P123 (EO20PO70EO20) as a template. The resultant samples were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption measurements (BET), UV-vis diffuse reflectance spectroscopy, photoluminescence (PL) spectra, Fourier transform infrared spectroscopy (FTIR) and thermal analyses (TG-DTA). In comparison with nondoped sample, RE-doped samples showed not only an increase in the surface areas and pore volumes, but also an inhibition of titania phase transition from anatase to rutile. Photo-degradation results revealed that RE-doped samples could greatly improve the photocatalytic activity, and the experimental degradation rates of methyl orange (MO) were higher than that catalyzed by undoped samples and Degussa P-25, obeyed the order of Nd(3+)>La(3+)>Y(3+). Nd-doped sample expressed the highest photoactivity and the optimal dosage was 0.25mol%, which resulted in MO degradation rates of 99.8% and 90.05% irradiation under UV for 60min and VL (λ>400nm) for 40h, respectively. The enhanced photocatalytic activity could be attributed to the higher specific area, good crystallinity, strong VL absorption and effective separation of photogenerated electron-hole pairs in the catalyst. Copyright © 2014 Elsevier B.V. All rights reserved.

  19. Visualization of melanoma tumor with lectin-conjugated rare-earth doped fluoride nanocrystals

    PubMed Central

    Dumych, Tetiana; Lutsyk, Maxym; Banski, Mateusz; Yashchenko, Antonina; Sojka, Bartlomiej; Horbay, Rostyslav; Lutsyk, Alexander; Stoika, Rostyslav; Misiewicz, Jan; Podhorodecki, Artur; Bilyy, Rostyslav

    2014-01-01

    Aim To develop specific fluorescent markers for melanoma tumor visualization, which would provide high selectivity and reversible binding pattern, by the use of carbohydrate-recognizing proteins, lectins, combined with the physical ability for imaging deep in the living tissues by utilizing red and near infrared fluorescent properties of specific rare-earth doped nanocrystals (NC). Methods B10F16 melanoma cells were inoculated to C57BL/6 mice for inducing experimental melanoma tumor. Tumors were removed and analyzed by lectin-histochemistry using LABA, PFA, PNA, HPA, SNA, GNA, and NPL lectins and stained with hematoxylin and eosin. NPL lectin was conjugated to fluorescent NaGdF4:Eu3+-COOH nanoparticles (5 nm) via zero length cross-linking reaction, and the conjugates were purified from unbound substances and then used for further visualization of histological samples. Fluorescent microscopy was used to visualize NPL-NaGdF4:Eu3+ with the fluorescent emission at 600-720 nm range. Results NPL lectin selectively recognized regions of undifferentiated melanoblasts surrounding neoangiogenic foci inside melanoma tumor, PNA lectin recognized differentiated melanoblasts, and LCA and WGA were bound to tumor stroma regions. NPL-NaGdF4:Eu3+ conjugated NC were efficiently detecting newly formed regions of melanoma tumor, confirmed by fluorescent microscopy in visible and near infrared mode. These conjugates possessed high photostability and were compatible with convenient xylene-based mounting systems and preserved intensive fluorescent signal at samples storage for at least 6 months. Conclusion NPL lectin-NaGdF4:Eu3+ conjugated NC permitted distinct identification of contours of the melanoma tissue on histological sections using red excitation at 590-610 nm and near infrared emission of 700-720 nm. These data are of potential practical significance for development of glycans-conjugated nanoparticles to be used for in vivo visualization of melanoma tumor. PMID:24891277

  20. Progress Towards Left-Handed Electromagnetic Waves in Rare-Earth Doped Crystals

    NASA Astrophysics Data System (ADS)

    Brewer, Nicholas Riley

    In 1968 Victor Veselago determined that a material with both a negative permittivity and negative permeability would have some extraordinary properties. The index of refraction of this material would be negative and light propagating inside would be 'left-handed'. This research went relatively unnoticed until the year 2000 when John Pendry discovered that a lens with an index of refraction of n = -1 could, in principle, have infinite resolution. Since 2000, research into negative index materials has exploded. The challenging part of this research is to get a material to respond to magnetic fields at optical frequencies. Artificially created metamaterials are able to achieve this and have been the focus of most negative index research. The long term goal of our project is to produce left-handed light in an atomic system. In order to do this, an atomic transition needs to be utilized that is magnetic dipole in character. Pure magnetic dipole transitions in the optical regime are more rare and fundamentally much weaker than the electric dipole transitions typically used in atomic physics experiments. They can be found, however, in the complex atomic structure of rare-earth elements. The 7F0 → 5D 1 transition in europium doped yttrium orthosilicate (Eu3+:Y 2SiO5) has a wavelength of 527.5 nm and is a pure magnetic dipole transition. We measured its dipole moment to be (0.063 +/- 0.005)mu B via Rabi oscillations, inferring a magnetization on the order of 10 -2 A/m. Demonstrating this large magnetic response at an optical frequency is a major first step in realizing left-handed light in atomic systems.

  1. FABRICATION AND PHOTOCATALYTIC PROPERTIES OF TiO2 NANOFILMS CO-DOPED WITH Fe3+ AND Bi3+ IONS

    NASA Astrophysics Data System (ADS)

    Gao, Qiongzhi; Liu, Xin; Liu, Wei; Liu, Fang; Fang, Yueping; Zhang, Shiying; Zhou, Wuyi

    2016-12-01

    In this work, the titanium dioxide (TiO2) nanofilms co-doped with Fe3+ and Bi3+ ions were successfully fabricated by the sol-gel method with dip-coating process. Methylene blue was used as the target degradation chemical to study the photocatalytic properties affected by different doping contents of Fe3+ and Bi3+ ions. The samples were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM) and infrared (IR) spectroscopy. The results indicated that both pure TiO2 nanofilms and single-doped samples possessed the photocatalytic activity in degradation of methylene blue. However, when the nanofilms co-doped with Fe3+ and Bi3+ ions were fabricated at the molar ratio of 3:1 (Fe3+:Bi3+), they exhibited the best photocatalytic activity after the heat treatment at 500∘C for 2h. The wettability property test indicated that the TiO2 nanofilms co-doped with Fe3+ and Bi3+ ions in the molar ratio 3:1 owned an excellent hydrophilic property.

  2. Electron microscopic and ion scattering studies of heteroepitaxial tin-doped indium oxide films

    NASA Astrophysics Data System (ADS)

    Kamei, Masayuki; Shigesato, Yuzo; Takaki, Satoru; Hayashi, Yasuo; Sasaki, Mikio; Haynes, Tony E.

    1994-08-01

    The microstructure of heteroepitaxial tin-doped indium oxide (ITO) films were studied in detail. The surface morphology of the heteroepitaxial ITO film consisted of square-shaped, in-plane oriented subgrains (˜300 Å) in contrast to that of the polycrystalline film (characteristic grain-subgrain structure). The subgrain boundaries were predominantly formed along the {110} planes in the ITO film and dislocations were observed primarily along the subgrain boundaries. Ion channeling measurements showed the dislocation density of this film to be approximately 3×1010/cm2, and the angular distribution of the ion channeling yield showed that the subgrains are aligned to within better than 0.3° (standard deviation).

  3. Dispersion and thermal properties of lithium aluminum silicate glasses doped with Cr3+ ions

    NASA Astrophysics Data System (ADS)

    El-Diasty, Fouad; Abdel-Baki, Manal; Abdel Wahab, Fathy A.; Darwish, Hussein

    2006-10-01

    A series of new lithium aluminum silicate (LAS) glass systems doped with chromium ion is prepared. The reflectance and transmittance of the glass slabs are recorded. By means of an iteration procedure, the glass refractive index n and the extinction coefficient k and their dispersions are obtained. Across a wide spectral range of 0.2-1.6 μm, the dispersion curves are used to determine the atomic and quantum constants of the prepared glasses. These findings provide the average oscillator wavelength, the average oscillator strength, oscillator energy, dispersion energy, lattice energy, and material dispersion of the glass materials to be calculated. For optical waveguide applications, the wavelength for zero material dispersion is obtained. Dilatometric measurements are performed and the thermal expansion coefficient is calculated to throw some light on the thermo-optical properties of the present glasses correlating them with their structure and the presence of nonbridging oxygen ions.

  4. Fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses containing lithium, zinc and lead.

    PubMed

    Venkatramu, V; Babu, P; Jayasankar, C K

    2006-02-01

    The influence of glass composition on the fluorescence properties of Eu3+ ions doped borate and fluoroborate glasses modified with Li+, Zn2+ and Pb2+ cations have been investigated. The magnitude of splittings of 7F1 levels are analyzed using crystal-field (CF) analysis. The relative intensities of 5D0 --> 7F2 to 5D0 --> 7F1 transitions, crystal-field strength parameters and decay times of the 5D0 level have been determined and are found to be lower for Pb based glasses than those of Zn/Li based glasses. The lifetimes of 5D0 level are found to increase when borate glasses are modified with pure fluorides than with oxides and oxyfluorides. The fluorescence decay of 5D0 level fits perfect single exponential in the Eu3+:glass systems studied which indicates the absence of energy transfer between Eu3+ ions in these glasses.

  5. Resistivity analysis of epitaxially grown, doped semiconductors using energy dependent secondary ion mass spectroscopy

    NASA Astrophysics Data System (ADS)

    Burnham, Shawn D.; Thomas, Edward W.; Doolittle, W. Alan

    2006-12-01

    A characterization technique is discussed that allows quantitative optimization of doping in epitaxially grown semiconductors. This technique uses relative changes in the host atom secondary ion (HASI) energy distribution from secondary ion mass spectroscopy (SIMS) to indicate relative changes in conductivity of the material. Since SIMS is a destructive process due to sputtering through a film, a depth profile of the energy distribution of sputtered HASIs in a matrix will contain information on the conductivity of the layers of the film as a function of depth. This process is demonstrated with Mg-doped GaN, with the Mg flux slowly increased through the film. Three distinct regions of conductivity were observed: one with Mg concentration high enough to cause compensation and thus high resistivity, a second with moderate Mg concentration and low resistivity, and a third with little to no Mg doping, causing high resistivity due to the lack of free carriers. During SIMS analysis of the first region, the energy distributions of sputtered Ga HASIs were fairly uniform and unchanging for a Mg flux above the saturation, or compensation, limit. For the second region, the Ga HASI energy distributions shifted and went through a region of inconsistent energy distributions for Mg flux slightly below the critical flux for saturation, or compensation. Finally, for the third region, the Ga HASI energy distributions then settled back into another fairly unchanging, uniform pattern. These three distinct regions were analyzed further through growth of Mg-doped step profiles and bulk growth of material at representative Mg fluxes. The materials grown at the two unchanging, uniform regions of the energy distributions yielded highly resistive material due to too high of Mg concentration and low to no Mg concentration, respectively. However, material grown in the transient energy distribution region with Mg concentration between that of the two highly resistive regions yielded low

  6. Single-step synthesis of Er3+ and Yb3+ ions doped molybdate/Gd2O3 core-shell nanoparticles for biomedical imaging

    NASA Astrophysics Data System (ADS)

    Kamińska, Izabela; Elbaum, Danek; Sikora, Bożena; Kowalik, Przemysław; Mikulski, Jakub; Felcyn, Zofia; Samol, Piotr; Wojciechowski, Tomasz; Minikayev, Roman; Paszkowicz, Wojciech; Zaleszczyk, Wojciech; Szewczyk, Maciej; Konopka, Anna; Gruzeł, Grzegorz; Pawlyta, Mirosława; Donten, Mikołaj; Ciszak, Kamil; Zajdel, Karolina; Frontczak-Baniewicz, Małgorzata; Stępień, Piotr; Łapiński, Mariusz; Wilczyński, Grzegorz; Fronc, Krzysztof

    2018-01-01

    Nanostructures as color-tunable luminescent markers have become major, promising tools for bioimaging and biosensing. In this paper separated molybdate/Gd2O3 doped rare earth ions (erbium, Er3+ and ytterbium, Yb3+) core-shell nanoparticles (NPs), were fabricated by a one-step homogeneous precipitation process. Emission properties were studied by cathodo- and photoluminescence. Scanning electron and transmission electron microscopes were used to visualize and determine the size and shape of the NPs. Spherical NPs were obtained. Their core-shell structures were confirmed by x-ray diffraction and energy-dispersive x-ray spectroscopy measurements. We postulated that the molybdate rich core is formed due to high segregation coefficient of the Mo ion during the precipitation. The calcination process resulted in crystallization of δ/ξ (core/shell) NP doped Er and Yb ions, where δ—gadolinium molybdates and ξ—molybdates or gadolinium oxide. We confirmed two different upconversion mechanisms. In the presence of molybdenum ions, in the core of the NPs, Yb3+-{{{{MoO}}}4}2- (∣2F7/2, 3T2〉) dimers were formed. As a result of a two 980 nm photon absorption by the dimer, we observed enhanced green luminescence in the upconversion process. However, for the shell formed by the Gd2O3:Er, Yb NPs (without the Mo ions), the typical energy transfer upconversion takes place, which results in red luminescence. We demonstrated that the NPs were transported into cytosol of the HeLa and astrocytes cells by endocytosis. The core-shell NPs are sensitive sensors for the environment prevailing inside (shorter luminescence decay) and outside (longer luminescence decay) of the tested cells. The toxicity of the NPs was examined using MTT assay.

  7. Performance and Comparison of Lithium-Ion Batteries Under Low-Earth-Orbit Mission Profiles

    NASA Technical Reports Server (NTRS)

    Reid, Concha M.; Smart, Marshall C.; Bugga, Ratnakumar V.; Manzo, Michelle A.; Miller, Thomas B.; Gitzendanner, Rob

    2007-01-01

    The performance of two 28 V, 25 Ah lithium-ion batteries is being evaluated under low-Earth-orbit mission profiles for satellite and orbiter applications. The batteries are undergoing life testing and have achieved over 12,000 cycles to 40 percent depth-of-discharge.

  8. Biogenic oxygen from Earth transported to the Moon by a wind of magnetospheric ions

    NASA Astrophysics Data System (ADS)

    Terada, Kentaro; Yokota, Shoichiro; Saito, Yoshifumi; Kitamura, Naritoshi; Asamura, Kazushi; Nishino, Masaki N.

    2017-01-01

    For five days of each lunar orbit, the Moon is shielded from solar wind bombardment by the Earth's magnetosphere, which is filled with terrestrial ions. Although the possibility of the presence of terrestrial nitrogen and noble gases in lunar soil has been discussed based on their isotopic composition 1 , complicated oxygen isotope fractionation in lunar metal 2,3 (particularly the provenance of a 16O-poor component) re­mains an enigma 4,5 . Here, we report observations from the Japanese spacecraft Kaguya of significant numbers of 1-10 keV O+ ions, seen only when the Moon was in the Earth's plasma sheet. Considering the penetration depth into metal of O+ ions with such energy, and the 16O-poor mass-independent fractionation of the Earth's upper atmosphere 6 , we conclude that biogenic terrestrial oxygen has been transported to the Moon by the Earth wind (at least 2.6 × 104 ions cm-2 s-1) and implanted into the surface of the lunar regolith, at around tens of nanometres in depth 3,4 . We suggest the possibility that the Earth's atmosphere of billions of years ago may be preserved on the present-day lunar surface.

  9. Rare-earth doped nanocomposites enable multiscale targeted short-wave infrared imaging of metastatic breast cancer

    NASA Astrophysics Data System (ADS)

    Pierce, Mark C.; Higgins, Laura M.; Ganapathy, Vidya; Kantamneni, Harini; Riman, Richard E.; Roth, Charles M.; Moghe, Prabhas V.

    2017-02-01

    We are investigating the ability of targeted rare earth (RE) doped nanocomposites to detect and track micrometastatic breast cancer lesions to distant sites in pre-clinical in vivo models. Functionalizing RE nanocomposites with AMD3100 promotes targeting to CXCR4, a recognized marker for highly metastatic disease. Mice were inoculated with SCP-28 (CXCR4 positive) and 4175 (CXCR4 negative) cell lines. Whole animal in vivo SWIR fluorescence imaging was performed after bioluminescence imaging confirmed tumor burden in the lungs. Line-scanning confocal fluorescence microscopy provided high-resolution imaging of RE nanocomposite uptake and native tissue autofluorescence in ex vivo lung specimens. Co-registered optical coherence tomography imaging allowed assessment of tissue microarchitecture. In conclusion, multiscale optical molecular imaging can be performed in pre-clinical models of metastatic breast cancer, using targeted RE-doped nanocomposites.

  10. Silicon rich nitride ring resonators for rare - earth doped telecommunications-band amplifiers pumped at the O-band.

    PubMed

    Xing, P; Chen, G F R; Zhao, X; Ng, D K T; Tan, M C; Tan, D T H

    2017-08-22

    Ring resonators on silicon rich nitride for potential use as rare-earth doped amplifiers pumped at 1310 nm with amplification at telecommunications-band are designed and characterized. The ring resonators are fabricated on 300 nm and 400 nm silicon rich nitride films and characterized at both 1310 nm and 1550 nm. We demonstrate ring resonators exhibiting similar quality factors exceeding 10,000 simultaneously at 1310 nm and 1550 nm. A Dysprosium-Erbium material system exhibiting photoluminescence at 1510 nm when pumped at 1310 nm is experimentally demonstrated. When used together with Dy-Er co-doped particles, these resonators with similar quality factors at 1310 nm and 1550 nm may be used for O-band pumped amplifiers for the telecommunications-band.

  11. Mars Ionosphere Meteoritic Ion Distributions -A Mixture of Earth and Venus Characteristics

    NASA Astrophysics Data System (ADS)

    Grebowsky, J. M.; Benna, M.; Collinson, G.; Mahaffy, P. R.

    2016-12-01

    The Neutral Gas and Ion Mass Spectrometer on the Mars Atmosphere and Volatile Evolution mission repeatedly observes metallic ions on MAVEN's traversals below 155 kilometers during special deep-dipping orbital campaigns. On such orbits which sample the topside of the main metal ion peak in the ablation region, three of the major metal ions seen at Earth (Na+, Mg+ and Fe+) are always detected. The relative composition of these species varies with the planetary locations of the deep-dip orbits as does the complexity of the altitude profiles of the metal ion concentrations. Quite frequently the decrease of the concentrations with altitude (observed on inbound or outbound legs of the orbit relative to periapsis) tracks the atmospheric density scale height, but only in the average sense. The individual concentration altitude profiles themselves typically have large coherent oscillations indicative of atmospheric gravity wave effects. The monotonically decreasing altitude trends are most characteristic of observations in the northern hemisphere, but there are orbits that encounter large concentration disturbances in the metal ion profiles. The latter are more prevalent in the southern hemisphere. The major background environment differences between the northern and southern hemispheres are the existence of large remanent magnetic fields in the southern hemisphere atmosphere, but not the north. It appears that there are two types of metal ion distributions. One type is associated with vertical diffusion profiles from the main metal ion peak arising in weak or no-magnetic field regions (like Venus). The other type exhibits the complex disturbances. The latter occur in regions where transport of the metal ions is controlled by the magnetic fields, through externally imposed electric fields and/or neutral wind-driven electrodynamic processes as at Earth. A comparison is made between the onset of the disturbed metal ion profiles with the ambient magnetic fields to isolate the

  12. Improving the performance of methylene blue sensitized photopolymer by doping with nickel ion

    NASA Astrophysics Data System (ADS)

    Aswathy, G.; Rajesh, C. S.; Sreekumar, K.; Joseph, R.; Kartha, C. Sudha

    2016-05-01

    Holographic performance of an economically cheap metal ion doped photopolymer material is presented. We investigated the effect of incorporation of nickel ion into the methylene blue sensitized poly (vinyl alcohol)/acrylamide (MBPVA/AA) photopolymer system. The composition and preliminary characterization of the developed photopolymer material is reported. The presence of nickel ion improves the diffraction efficiency, stability of the material and it operates in a wide range of spatial frequencies (550-2000 lines/mm) at exposure energy of 100 mJ/cm2. When nickel ion concentration was 0.01 mM, maximum diffraction efficiency of 84% at exposure energy of 100 mJ/cm2 with spatial frequency 1335 lines/mm could be achieved for gratings recorded using wavelength of 632.8 nm. The material showed panchromaticity with more than 70% diffraction efficiency in both blue and green regions. Effects of humidity and temperature on the stored gratings were studied by keeping films in different environmental conditions. Suitability of recording large area holograms was also explored.

  13. Magnetic properties of manganites doped with gallium, iron, and chromium ions

    SciT

    Troyanchuk, I. O., E-mail: troyan@physics.by; Bushinsky, M. V.; Tereshko, N. V.

    The magnetization and the crystal structure of the La{sub 0.7}Sr{sub 0.3}Mn{sub 1−x}M{sub x}O{sub 3} (M = Ga, Fe, Cr; x ≤ 0.3) systems are studied. The substitution of gallium and chromium is shown to cause phase separation into antiferromagnetic and ferromagnetic phases, whereas the substitution of iron for manganese stabilizes a spinglass state. The ferromagnetic phase in the chromium-substituted compositions is much more stable than that in the case of substitution by iron ions or diamagnetic gallium ions. The magnetic properties are explained in terms of the model of superexchange interactions and the localization of most e{sub g} electrons ofmore » manganese. The stabilization of ferromagnetism in the chromium-substituted compositions can be caused by the fact that the positive and negative contributions to the superexchange interaction between Mn{sup 3+} and Cr{sup 3+} ions are close to each other but the antiferromagnetic part of the exchange is predominant. Moreover, some chromium ions are in the tetravalent state, which maintains the optimum doping conditions.« less

  14. Ab initio calculations on the positive ions of the alkaline-earth oxides, fluorides, and hydroxides

    NASA Technical Reports Server (NTRS)

    Partridge, H.; Langhoff, S. R.; Bauschlicher, C. W., Jr.

    1986-01-01

    Theoretical dissociation energies are presented for the alkaline-earth fluoride, hydroxide, and oxide positive ions that are considered to be accurate to 0.1-0.2 eV. The r(e) for the positive ions are found to be consistently shorter than the corresponding neutrals by 0.07 + or -0.02 A. The bonding in the ground states is demonstrated to be of predominantly M + 2 X - character. The a 3 Pi and A 1 Pi are found to lie considerably above the X 1 Sigma + ground states of the alkaline-earth fluoride and hydroxide positive ions. The overall agreement of the theoretical ionization potentials with the available experimental appearance potentials is satisfactory; these values should represent the most accurate and consistent set available.

  15. Tailored white light emission in Eu3+/Dy3+ doped tellurite glass phosphors containing Al3+ ions

    NASA Astrophysics Data System (ADS)

    Walas, Michalina; Piotrowski, Patryk; Lewandowski, Tomasz; Synak, Anna; Łapiński, Marcin; Sadowski, Wojciech; Kościelska, Barbara

    2018-05-01

    Tellurite glass systems modified by addition of aluminum fluoride AlF3 have been successfully synthesized as host matrices for optically active rare earth ions RE3+ (RE3+ = Eu3+, Dy3+). Samples with different Eu3+ to Dy3+ molar ratio have been studied in order to determine possibility of white light emission via UV excitation. Structural investigations confirmed amorphous character of materials whereas spectroscopic studies brought more insight into glass network's nature. FTIR results shown presence of two features related to tellurite glass matrix (in 490-935 cm-1 spectral region) and another one (940-1250 cm-1) due to aluminum addition. Especially, Al-O and Te-O-Al bonds of AlO4 tetrahedrons have been found. AlO4 units are considered as glass formers that improve network's strength and thermal resistivity against devitrification. Based on XPS studies of Al3+ photoelectron band the existence of Al-O and also Al-F bonds have been examined. Moreover, signals originating from Eu3+ and Dy3+ have been found confirming their valence state. Luminescence results revealed possibility of simultaneous UV excitation of Eu3+ and Dy3+ ions. Excitation with λexc = 390 and 393 nm resulted in white light generation starting from warm white to neutral and cool white depending on Eu3+ concentration and used excitation wavelength. Additionally, increase of decay lifetime of Eu3+ induced by Al3+ presence have been revealed based on luminescence decay analysis. Thus, tellurite glass systems modified by AlF3 and doped with Eu3+/Dy3+ may be considered as promising candidates for white light emitting sources.

  16. Observing quantum control of up-conversion luminescence in Dy3+ ion doped glass from weak to intermediate shaped femtosecond laser fields

    NASA Astrophysics Data System (ADS)

    Liu, Pei; Cheng, Wenjing; Yao, Yunhua; Xu, Cheng; Zheng, Ye; Deng, Lianzhong; Jia, Tianqing; Qiu, Jianrong; Sun, Zhenrong; Zhang, Shian

    2017-11-01

    Controlling the up-conversion luminescence of rare-earth ions in real-time, in a dynamical and reversible manner, is very important for their application in laser sources, fiber-optic communications, light-emitting diodes, color displays and biological systems. In previous studies, the up-conversion luminescence control mainly focused on the weak femtosecond laser field. Here, we further extend this control behavior from weak to intermediate femtosecond laser fields. In this work, we experimentally and theoretically demonstrate that the up-conversion luminescence in Dy3+ ion doped glass can be artificially controlled by a π phase step modulation, but the up-conversion luminescence control behavior will be affected by the femtosecond laser intensity, and the up-conversion luminescence is suppressed by lower laser intensity while enhanced by higher laser intensity. We establish a new theoretical model (i.e. the fourth-order perturbation theory) to explain the physical control mechanism by considering the two- and four-photon absorption processes, and the theoretical results show that the relative weight of four-photon absorption in the whole excitation process will increase with the increase in laser intensity, and the interference between two- and four-photon absorptions results in up-conversion luminescence control modulation under different laser intensities. These theoretical and experimental works can provide a new method to control and understand up-conversion luminescence in rare-earth ions, and also may open a new opportunity to the related application areas of rare-earth ions.

  17. Multicolor and near-infrared electroluminescence from the light-emitting devices with rare-earth doped TiO{sub 2} films

    SciT

    Zhu, Chen; Gao, Zhifei; Wang, Canxing

    2015-09-28

    We report on multicolor and near-infrared electroluminescence (EL) from the devices using rare-earth doped TiO{sub 2} (TiO{sub 2}:RE) films as light-emitting layers, which are ascribed to the impact excitation of RE{sup 3+} ions, with the EL onset voltages below 10 V. The devices are in the structure of ITO/TiO{sub 2}:RE/SiO{sub 2}/Si, in which the SiO{sub 2} layer is ∼10 nm thick and RE includes Eu, Er, Tm, Nd, and so on. With sufficiently high positive voltage applied on the ITO electrode, the conduction electrons in Si can tunnel into the conduction band of SiO{sub 2} layer via the trap-assisted tunneling mechanism, gainingmore » the potential energy ∼4 eV higher than the conduction band edge of TiO{sub 2}. Therefore, as the electrons in the SiO{sub 2} layer drift into the TiO{sub 2}:RE layer, they become hot electrons. Such hot electrons impact-excite the RE{sup 3+} ions incorporated into the TiO{sub 2} host, leading to the characteristic emissions.« less

  18. Li-adsorption on doped Mo2C monolayer: A novel electrode material for Li-ion batteries

    NASA Astrophysics Data System (ADS)

    Mehta, Veenu; Tankeshwar, K.; Saini, Hardev S.

    2018-04-01

    A first principle calculation has been used to study the electronic and magnetic properties of pristine and N/Mn-doped Mo2C with and without Li-adsorption. The pseudopotential method implemented in SIESTA code based on density functional theory with generalized gradient approximation (GGA) as exchange-correlation (XC) potential has been employed. Our calculated results revealed that the Li gets favorably adsorbed on the hexagonal centre in pristine Mo2C and at the top of C-atom in case of N/Mn-doped Mo2C. The doping of Mn and N atom increases the adsorption of Li in Mo2C monolayer which may results in enhancement of storage capacity in Li-ion batteries. The metallic nature of Li-adsorbed pristine and N/Mn-doped Mo2C monolayer implies a good electronic conduction which is crucial for anode materials for its applications in rechargeable batteries. Also, the open circuit voltage for single Li-adsorption in doped Mo2C monolayer comes in the range of 0.4-1.0 eV which is the optimal range for any material to be used as an anode material. Our result emphasized the enhanced performance of doped Mo2C as an anode material in Li-ion batteries.

  19. Green synthesis of boron doped graphene and its application as high performance anode material in Li ion battery

    SciT

    Sahoo, Madhumita; Sreena, K.P.; Vinayan, B.P.

    2015-01-15

    Graphical abstract: Boron doped graphene (B-G), synthesized by simple hydrogen induced reduction technique using boric acid as boron precursor, have more uneven surface as a result of smaller bonding distance of boron compared to carbon, showed high capacity and high rate capability compared to pristine graphene as an anode material for Li ion battery application. - Abstract: The present work demonstrates a facile route for the large-scale, catalyst free, and green synthesis approach of boron doped graphene (B-G) and its use as high performance anode material for Li ion battery (LIB) application. Boron atoms were doped into graphene framework withmore » an atomic percentage of 5.93% via hydrogen induced thermal reduction technique using graphite oxide and boric acid as precursors. Various characterization techniques were used to confirm the boron doping in graphene sheets. B-G as anode material shows a discharge capacity of 548 mAh g{sup −1} at 100 mA g{sup −1} after 30th cycles. At high current density value of 1 A g{sup −1}, B-G as anode material enhances the specific capacity by about 1.7 times compared to pristine graphene. The present study shows a simplistic way of boron doping in graphene leading to an enhanced Li ion adsorption due to the change in electronic states.« less

  20. Studies of the Core Conditions of the Earth and Super-Earths Using Intense Ion Beams at FAIR

    NASA Astrophysics Data System (ADS)

    Tahir, N. A.; Lomonosov, I. V.; Borm, B.; Piriz, A. R.; Shutov, A.; Neumayer, P.; Bagnoud, V.; Piriz, S. A.

    2017-09-01

    Using detailed numerical simulations, we present the design of an experiment that will generate samples of iron under extreme conditions of density and pressure believed to exist in the interior of the Earth and interior of extrasolar Earth-like planets. In the proposed experiment design, an intense uranium beam is used to implode a multilayered cylindrical target that consists of a thin Fe cylinder enclosed in a thick massive W shell. Such intense uranium beams will be available at the heavy-ion synchrotron, SIS100, at the Facility for Antiprotons and Ion Research (FAIR), at Darmstadt, which is under construction and will become operational in the next few years. It is expected that the beam intensity will increase gradually over a couple of years to its maximum design value. Therefore, in our studies, we have considered a wide range of beam parameters, from the initial beam intensity (“Day One”) to the maximum specified value. It is also worth noting that two different focal spot geometries have been used. In one case, a circular focal spot with a Gaussian transverse intensity distribution is considered, whereas in the other case, an annular focal spot is used. With these two beam geometries, one can access different parts of the Fe phase diagram. For example, heating the sample with a circular focal spot generates a hot liquid state, while an annular focal spot can produce a highly compressed liquid or a highly compressed solid phase depending on the beam intensity.

  1. N doped ZnO and ZnO nanorods based p-n homojunction fabricated by ion implantation

    NASA Astrophysics Data System (ADS)

    Chakraborty, Mohua; Thangavel, R.; Asokan, K.

    2018-05-01

    Nitrogen (N) doped and undoped Zinc Oxide (ZnO) nanorod p-n homojunctions were fabricated by ion implantation method. The structural and optical characterizations showed that the N atoms doped into the ZnO crystal lattice. The UV-Vis absorption spectra revealed shift in optical absorption edge towards higher wavelength with ion implantation on ZnO, which attributed N acceptor levels above the valence band. The current-voltage (I-V) measurements exhibit a typical semiconductor rectification characteristic indicating the electrical conductivity of the N-doped ZnO nanorod have p-type conductivity. Moreover, a high photocurrent response has been observed with these p-n homojunctions.

  2. Studies on hydrothermal synthesis of photolumniscent rare earth (Eu3+ & Tb3+) doped NG@FeMoO4 for enhanced visible light photodegradation of methylene blue dye

    NASA Astrophysics Data System (ADS)

    Singh, R.; Kumar, M.; Khajuria, H.; Sharma, S.; Sheikh, H. Nawaz

    2018-02-01

    FeMoO4 nanorods and their rare earth (Eu3+ and Tb3+) doped composites with nitrogen doped graphene (NG) were synthesized by facile hydrothermal method in aqueous medium. X-ray diffraction (XRD) analysis of the as-synthesized samples was done to study the phase purity and crystalline nature. FTIR and Raman Spectroscopy have been studied for investigating the bonding in nanostructures. The surface morphology of the samples was investigated with field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). The photolumniscent nature of the samples was investigated by the using the fluorescence spectrophotometer. The photocatalytic degradation efficiency of the prepared pure FeMoO4 and its rare earth doped composites with nitrogen doped graphene was evaluated as function of visible light irradiation versus concentration of methylene blue (MB dye). The prepared nanocomposites show enhanced photocatalytic efficiency as compared to the bare FeMoO4 nanorods.

  3. Nonthermal ions and associated magnetic field behavior at a quasi-parallel earth's bow shock

    NASA Technical Reports Server (NTRS)

    Wilkinson, W. P.; Pardaens, A. K.; Schwartz, S. J.; Burgess, D.; Luehr, H.; Kessel, R. L.; Dunlop, M.; Farrugia, C. J.

    1993-01-01

    Attention is given to ion and magnetic field measurements at the earth's bow shock from the AMPTE-UKS and -IRM spacecraft, which were examined in high time resolution during a 45-min interval when the field remained closely aligned with the model bow shock normal. Dense ion beams were detected almost exclusively in the midst of short-duration periods of turbulent magnetic field wave activity. Many examples of propagation at large elevation angles relative to the ecliptic plane, which is inconsistent with reflection in the standard model shock configuration, were discovered. The associated waves are elliptically polarized and are preferentially left-handed in the observer's frame of reference, but are less confined to the maximum variance plane than other previously studied foreshock waves. The association of the wave activity with the ion beams suggests that the former may be triggered by an ion-driven instability, and possible candidates are discussed.

  4. Demonstration of ultra-low NA rare-earth doped step index fiber for applications in high power fiber lasers.

    PubMed

    Jain, Deepak; Jung, Yongmin; Barua, Pranabesh; Alam, Shaiful; Sahu, Jayanta K

    2015-03-23

    In this paper, we report the mode area scaling of a rare-earth doped step index fiber by using low numerical aperture. Numerical simulations show the possibility of achieving an effective area of ~700 um² (including bend induced effective area reduction) at a bend diameter of 32 cm from a 35 μm core fiber with a numerical aperture of 0.038. An effective single mode operation is ensured following the criterion of the fundamental mode loss to be lower than 0.1 dB/m while ensuring the higher order modes loss to be higher than 10 dB/m at a wavelength of 1060 nm. Our optimized modified chemical vapor deposition process in conjunction with solution doping process allows fabrication of an Yb-doped step index fiber having an ultra-low numerical aperture of ~0.038. Experimental results confirm a Gaussian output beam from a 35 μm core fiber validating our simulation results. Fiber shows an excellent laser efficiency of ~81%and aM² less than 1.1.

  5. One-step synthesis of layered yttrium hydroxides in immiscible liquid-liquid systems: Intercalation of sterically-bulky hydrophobic organic anions and doping of europium ions

    NASA Astrophysics Data System (ADS)

    Watanabe, Mebae; Fujihara, Shinobu

    2014-02-01

    Inorganic-organic layered rare-earth compounds were synthesized on the basis of a biphasic liquid-liquid system in one pot. Layered yttrium hydroxides (LYHs) were chosen as a host material for the intercalation of hydrophobic organic guest anions such as benzoate, sebacate, or laurate. In a typical synthesis, an organic phase dissolving carboxylic acid was placed in contact with an equal amount of an aqueous phase dissolving yttrium nitrate n-hydrate and urea. At elevated temperatures up to 80 °C, urea was hydrolyzed to release hydroxyl anions which were used to form yttrium hydroxide layers. LYHs were then precipitated with the intercalation of carboxylate anions delivered from the organic phase under the distribution law. The structure and the morphology of the LYHs could be modulated by the intercalated anions. Doped with Eu3+ ions, the LYHs exhibited red photoluminescence which was enhanced by the intercalated anions due to the antenna effect.

  6. Nitrogen-Doped Hollow Carbon Nanospheres for High-Performance Li-Ion Batteries.

    PubMed

    Yang, Yufen; Jin, Song; Zhang, Zhen; Du, Zhenzhen; Liu, Huarong; Yang, Jia; Xu, Hangxun; Ji, Hengxing

    2017-04-26

    N-doped carbon materials is of particular attraction for anodes of lithium-ion batteries (LIBs) because of their high surface areas, superior electrical conductivity, and excellent mechanical strength, which can store energy by adsorption/desorption of Li + at the interfaces between the electrolyte and electrode. By directly carbonization of zeolitic imidazolate framework-8 nanospheres synthesized by an emulsion-based interfacial reaction, we obtained N-doped hollow carbon nanospheres with tunable shell thickness (20 nm to solid sphere) and different N dopant concentrations (3.9 to 21.7 at %). The optimized anode material possessed a shell thickness of 20 nm and contained 16.6 at % N dopants that were predominately pyridinic and pyrrolic. The anode delivered a specific capacity of 2053 mA h g -1 at 100 mA g -1 and 879 mA h g -1 at 5 A g -1 for 1000 cycles, implying a superior cycling stability. The improved electrochemical performance can be ascribed to (1) the Li + adsorption dominated energy storage mechanism prevents the volume change of the electrode materials, (2) the hollow nanostructure assembled by the nanometer-sized primary particles prevents the agglomeration of the nanoparticles and favors for Li + diffusion, (3) the optimized N dopant concentration and configuration facilitate the adsorption of Li + ; and (4) the graphitic carbon nanostructure ensures a good electrical conductivity.

  7. Enhancement of the photocatalytic activity of TiO(2) by doping it with calcium ions.

    PubMed

    Akpan, U G; Hameed, B H

    2011-05-01

    Titanium dioxide (TiO(2)) with an enhanced photocatalytic activity was developed by doping it with calcium ions through a sol-gel method. The developed photocatalysts were characterized by Fourier transform infrared (FTIR) spectroscopy, N(2) physisorption, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction. Their surface morphologies were studied using surface scanning electron microscopy (SEM). The XPS analyses confirmed the presence of Ti, O, Ca, and C in the Ca-doped TiO(2) sample. The activities of the catalysts were evaluated by photocatalytic degradation of an azo dye, acid red 1 (AR1), using UV light irradiation. The results of the investigations revealed that the samples calcined at 300 °C for 3.6h in a cyclic (2 cycles) mode had the best performance. Lower percentage dopant, 0.3-1.0 wt.%, enhanced the photocatalytic activity of TiO(2), with the best at 0.5 wt.% Ca-TiO(2). The performance of 0.5 wt.% Ca-TiO(2) in the degradation of AR1 was far superior to that of a commercial anatase TiO(2) Sigma product CAS No. 1317-70-0. The effect of pH on the degradation of AR1 was studied, and the pH of the dye solution exerted a great influence on the degradation of the dye. Copyright © 2011 Elsevier Inc. All rights reserved.

  8. Luminescence variations in hydroxyapatites doped with Eu2+ and Eu3+ ions.

    PubMed

    Graeve, Olivia A; Kanakala, Raghunath; Madadi, Abhiram; Williams, Brandon C; Glass, Katelyn C

    2010-05-01

    We present a detailed analysis of the luminescence behavior of europium-doped hydroxyapatite (HAp) and calcium-deficient hydroxyapatite (Ca-D HAp) nanopowders. The results show that, while both powders are similar in crystallite size, particle size, and morphology, the luminescence behavior differs significantly. For the HAp:Eu powders, the emission is clearly from Eu(3+) ions and corresponds to typical (5)D(0) --> (7)F(J) emissions, whereas for the Ca-D HAp:Eu powders, we also see a broad emission with two peaks at 420 and 445 nm, corresponding to the 4f(6)5d(1) --> 4f(7) ((8)S(7/2)) transition of Eu(2+). The powders are weakly luminescent in the as-synthesized state, as expected for combustion-synthesized materials and have higher emission intensities as the heat treatment temperature is increased. Luminescence spectra obtained using an excitation wavelength of 254 nm are weak for all samples. Excitation wavelengths of 305, 337, and 359 nm, are better at promoting the Eu(3+) and Eu(2+) emissions in hydroxyapatites. We propose that fluorescence measurements are an excellent way of qualitatively determining the phase composition of europium-doped hydroxyapatite powders, since powders that exhibit a blue emission contain substantial amounts of Ca-D HAp, allowing the determination of the presence of this phase in mixed-phase hydroxyapatites. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

  9. Phosphorus-doped silicon nanorod anodes for high power lithium-ion batteries.

    PubMed

    Yan, Chao; Liu, Qianru; Gao, Jianzhi; Yang, Zhibo; He, Deyan

    2017-01-01

    Heavy-phosphorus-doped silicon anodes were fabricated on CuO nanorods for application in high power lithium-ion batteries. Since the conductivity of lithiated CuO is significantly better than that of CuO, after the first discharge, the voltage cut-off window was then set to the range covering only the discharge-charge range of Si. Thus, the CuO core was in situ lithiated and acts merely as the electronic conductor in the following cycles. The Si anode presented herein exhibited a capacity of 990 mAh/g at the rate of 9 A/g after 100 cycles. The anode also presented a stable rate performance even at a current density as high as 20 A/g.

  10. New Er3+-doped phosphate glass for ion-exchanged waveguide amplifiers

    NASA Astrophysics Data System (ADS)

    Jiang, Shibin; Luo, Tao; Hwang, Bor-Chyuan; Nunzi Conti, Gualtiero; Myers, Michael J.; Rhonehouse, Daniel L.; Honkanen, Seppo; Peyghambarian, Nasser

    1998-12-01

    A new Er(superscript 3+)-doped phosphate glass exhibiting an excellent durability in both boiling water and NaNO(subscript 3) molten salt is developed. The ion-exchange process of this glass is investigated by treating glass samples in a variety of salt baths with various exposure times. A planar waveguide with one mode at 1.54 micrometers and three modes at 632.8 nm is demonstrated. The spectral properties of Er(superscript 3+) in this glass are characterized by measuring absorption and emission spectra and fluorescence lifetimes. The emission cross section of Er(superscript 3+) in this glass is calculated to be 0.76 X 10(superscript 20) cm(superscript 2) using McCumber theory.

  11. Source Distributions of Substorm Ions Observed in the Near-Earth Magnetotail

    NASA Technical Reports Server (NTRS)

    Ashour-Abdalla, M.; El-Alaoui, M.; Peroomian, V.; Walker, R. J.; Raeder, J.; Frank, L. A.; Paterson, W. R.

    1999-01-01

    This study employs Geotail plasma observations and numerical modeling to determine sources of the ions observed in the near-Earth magnetotail near midnight during a substorm. The growth phase has the low-latitude boundary layer as its most important source of ions at Geotail, but during the expansion phase the plasma mantle is dominant. The mantle distribution shows evidence of two distinct entry mechanisms: entry through a high latitude reconnection region resulting in an accelerated component, and entry through open field lines traditionally identified with the mantle source. The two entry mechanisms are separated in time, with the high-latitude reconnection region disappearing prior to substorm onset.

  12. Application of Freeze-Dried Powders of Genetically Engineered Microbial Strains as Adsorbents for Rare Earth Metal Ions.

    PubMed

    Moriwaki, Hiroshi; Masuda, Reiko; Yamazaki, Yuki; Horiuchi, Kaoru; Miyashita, Mari; Kasahara, Jun; Tanaka, Tatsuhito; Yamamoto, Hiroki

    2016-10-12

    The adsorption behaviors of the rare earth metal ions onto freeze-dried powders of genetically engineered microbial strains were compared. Cell powders obtained from four kinds of strains, Bacillus subtilis 168 wild type (WT), lipoteichoic acid-defective (ΔLTA), wall teichoic acid-defective (ΔWTA), and cell wall hydrolases-defective (EFKYOJLp) strains, were used as an adsorbent of the rare earth metal ions at pH 3. The adsorption ability of the rare earth metal ions was in the order of EFKYOJLp > WT > ΔLTA > ΔWTA. The order was the same as the order of the phosphorus quantity of the strains. This result indicates that the main adsorption sites for the ions are the phosphate groups and the teichoic acids, LTA and WTA, that contribute to the adsorption of the rare earth metal ions onto the cell walls. The contribution of WTA was clearly greater than that of LTA. Each microbial powder was added to a solution containing 16 kinds of rare earth metal ions, and the removals (%) of each rare earth metal ion were obtained. The scandium ion showed the highest removal (%), while that of the lanthanum ion was the lowest for all the microbial powders. Differences in the distribution coefficients between the kinds of lanthanide ions by the EFKYOJLp and ΔWTA powders were greater than those of the other strains. Therefore, the EFKYOJLp and ΔWTA powders could be applicable for the selective extraction of the lanthanide ions. The ΔLTA powder coagulated by mixing with a rare earth metal ion, although no sedimentation of the WT or ΔWTA powder with a rare earth metal ion was observed under the same conditions. The EFKYOJLp powder was also coagulated, but its flocculating activity was lower than that of ΔLTA. The ΔLTA and EFKYOJLp powders have a long shape compared to those of the WT or ΔWTA strain. The shapes of the cells will play an important role in the sedimentation of the microbial powders with rare earth metal ions. As the results, three kinds of the genetically

  13. Accelerated ions and self-excited Alfvén waves at the Earth's bow shock

    NASA Astrophysics Data System (ADS)

    Berezhko, E. G.; Taneev, S. N.; Trattner, K. J.

    2011-07-01

    The diffuse energetic ion event and related Alfvén waves upstream of the Earth's bow shock, measured by AMPTE/IRM satellite on 29 September 1984, 06:42-07:22 UT, was studied using a self-consistent quasi-linear theory of ion diffusive shock acceleration and associated Alfvén wave generation. The wave energy density satisfies a wave kinetic equation, and the ion distribution function satisfies the diffusive transport equation. These coupled equations are solved numerically, and calculated ion and wave spectra are compared with observations. It is shown that calculated steady state ion and Alfvén wave spectra are established during the time period of about 1000 s. Alfvén waves excited by accelerated ions are confined within the frequency range (10-2 to 1) Hz, and their spectral peak with the wave amplitude δB ≈ B comparable to the interplanetary magnetic field value B corresponds to the frequency 2 × 10-2 Hz. The high-frequency part of the wave spectrum undergoes absorption by thermal protons. It is shown that the observed ion spectra and the associated Alfvén wave spectra are consistent with the theoretical prediction.

  14. A rare-earth-magnet ion trap for confining low-Z, bare nuclei

    NASA Astrophysics Data System (ADS)

    Brewer, Samuel M.; Tan, Joseph N.

    2009-05-01

    Simplifications in the theory for Rydberg states of hydrogenlike ions allow a substantial improvement in the accuracy of predicted levels, which can yield information on the values of fundamental constants and test theory if they can be compared with precision frequency measurements.[1] We consider the trapping of bare nuclei (fully-stripped) to be used in making Rydberg states of one-electron ions with atomic number 1< Z < 11. Numerical simulation is used here to study ion confinement in a compact, Penning-style ion trap consisting of electrodes integrated with rare-earth permanent magnets, and to model the capture of charge-state-selected ions extracted from an electron beam ion trap (EBIT). An experimental apparatus adapted to the NIST EBIT will also be discussed. Reference: [1] U.D. Jentschura, P.J. Mohr, J.N. Tan, and B.J. Wundt, ``Fundamental constants and tests of theory in Rydberg states of hydrogenlike ions,'' Phys. Rev. Lett. 100, 160404 (2008).

  15. Effect of rare earth doping on optical and spectroscopic characteristics of BaZrO3:Eu3+,Tb3+ perovskites

    NASA Astrophysics Data System (ADS)

    Katyayan, Shambhavi; Agrawal, Sadhana

    2018-06-01

    This paper reports structural investigations of rare earth doped BaZrO3 phosphors synthesized by Solid state reaction technique with varying concentrations of Eu3+ and Tb3+ from 0 mol% to 2 mol%. The synthesized phosphors show enhanced variable emissions in the visible region corresponding to different hypersensitive electronic transitions of Eu3+ and Tb3+ ions. With cubic structure confirmed in XRD analysis, the FESEM images show uniform grain connectivity and homogeneity of prepared samples. The TEM micrographs of the synthesized phosphors show agglomerated irregular structures. The synthesized phosphors were also subjected to FTIR, Raman, EDXS analysis along with studies of thermoluminescent and photoluminescent characteristics. On subjecting to 229 nm (UV) excitation, the phosphors show enhanced PL emissions corresponding to 571 nm (5D0-7F0), 591 nm (5D0-7F1), 615 nm (5D0-7F2) and 678 nm (5D0-7F4) hypersensitive transitions of Eu3+ ions and emission peaks at 489 nm (5D4-7F6), 539 nm (5D4-7F5), 589 nm (5D4-7F4) and 632 nm (5D4-7F3) accounting for electronic transitions of Tb3+ ions respectively. The computed average PL lifetime is 14.014 s. In the TL analysis, the second order of kinetics with the activation energy varying from 5.0 × 10‑1 eV to 6.6 × 10‑1 eV is reported. The maximum TL lifetime is estimated as 19.4985 min in the TL lifetime analysis.

  16. Effect of rare earth doping on optical and spectroscopic characteristics of BaZrO3:Eu3+,Tb3+ perovskites.

    PubMed

    Katyayan, Shambhavi; Agrawal, Sadhana

    2018-04-04

    This paper reports structural investigations of rare earth doped BaZrO 3 phosphors synthesized by Solid state reaction technique with varying concentrations of Eu 3+ and Tb 3+ from 0 mol% to 2 mol%. The synthesized phosphors show enhanced variable emissions in the visible region corresponding to different hypersensitive electronic transitions of Eu 3+ and Tb 3+ ions. With cubic structure confirmed in XRD analysis, the FESEM images show uniform grain connectivity and homogeneity of prepared samples. The TEM micrographs of the synthesized phosphors show agglomerated irregular structures. The synthesized phosphors were also subjected to FTIR, Raman, EDXS analysis along with studies of thermoluminescent and photoluminescent characteristics. On subjecting to 229 nm (UV) excitation, the phosphors show enhanced PL emissions corresponding to 571 nm ( 5 D 0 - 7 F 0 ), 591 nm ( 5 D 0 - 7 F 1 ), 615 nm ( 5 D 0 - 7 F 2 ) and 678 nm ( 5 D 0 - 7 F 4 ) hypersensitive transitions of Eu 3+ ions and emission peaks at 489 nm ( 5 D 4 - 7 F 6 ), 539 nm ( 5 D 4 - 7 F 5 ), 589 nm ( 5 D 4 - 7 F 4 ) and 632 nm ( 5 D 4 - 7 F 3 ) accounting for electronic transitions of Tb 3+ ions respectively. The computed average PL lifetime is 14.014 s. In the TL analysis, the second order of kinetics with the activation energy varying from 5.0 × 10 -1 eV to 6.6 × 10 -1 eV is reported. The maximum TL lifetime is estimated as 19.4985 min in the TL lifetime analysis.

  17. Solid Phase Luminescence of Several Rare Earth Ions on Ion-Exchange Films

    NASA Technical Reports Server (NTRS)

    Tanner, Stephen P.; Street, Kenneth W., Jr.

    1999-01-01

    The development and characterization of a novel ion-exchange film for solid-phase fluorometry and phosphorimetry is reported. This new cation-exchange material is suitable for spectroscopic applications in the ultraviolet and visible regions. It is advantageous because it, as a single entity, is easily recovered from solution and mounted in the spectrofluorometers. After preconcentration on the film, the luminescence intensity of lanthanide ions is several orders of magnitude greater than that of the corresponding solution, depending on the volume of solution and the amount of film. This procedure allows emission spectral measurements and determination of lanthanide ions at solution concentrations of < 5 (micro)g/L. The film may be stored for subsequent reuse or as a permanent record of the analysis. The major drawback to the use of the film is slow uptake of analyte due to diffusion limitations.

  18. N/S Co-doped Carbon Derived From Cotton as High Performance Anode Materials for Lithium Ion Batteries

    PubMed Central

    Xiong, Jiawen; Pan, Qichang; Zheng, Fenghua; Xiong, Xunhui; Yang, Chenghao; Hu, Dongli; Huang, Chunlai

    2018-01-01

    Highly porous carbon with large surface areas is prepared using cotton as carbon sources which derived from discard cotton balls. Subsequently, the sulfur-nitrogen co-doped carbon was obtained by heat treatment the carbon in presence of thiourea and evaluated as Lithium-ion batteries anode. Benefiting from the S, N co-doping, the obtained S, N co-doped carbon exhibits excellent electrochemical performance. As a result, the as-prepared S, N co-doped carbon can deliver a high reversible capacity of 1,101.1 mA h g−1 after 150 cycles at 0.2 A g−1, and a high capacity of 531.2 mA h g−1 can be observed even after 5,000 cycles at 10.0 A g−1. Moreover, excellently rate capability also can be observed, a high capacity of 689 mA h g−1 can be obtained at 5.0 A g−1. This superior lithium storage performance of S, N co-doped carbon make it as a promising low-cost and sustainable anode for high performance lithium ion batteries. PMID:29755966

  19. N/S Co-doped Carbon Derived From Cotton as High Performance Anode Materials for Lithium Ion Batteries.

    PubMed

    Xiong, Jiawen; Pan, Qichang; Zheng, Fenghua; Xiong, Xunhui; Yang, Chenghao; Hu, Dongli; Huang, Chunlai

    2018-01-01

    Highly porous carbon with large surface areas is prepared using cotton as carbon sources which derived from discard cotton balls. Subsequently, the sulfur-nitrogen co-doped carbon was obtained by heat treatment the carbon in presence of thiourea and evaluated as Lithium-ion batteries anode. Benefiting from the S, N co-doping, the obtained S, N co-doped carbon exhibits excellent electrochemical performance. As a result, the as-prepared S, N co-doped carbon can deliver a high reversible capacity of 1,101.1 mA h g -1 after 150 cycles at 0.2 A g -1 , and a high capacity of 531.2 mA h g -1 can be observed even after 5,000 cycles at 10.0 A g -1 . Moreover, excellently rate capability also can be observed, a high capacity of 689 mA h g -1 can be obtained at 5.0 A g -1 . This superior lithium storage performance of S, N co-doped carbon make it as a promising low-cost and sustainable anode for high performance lithium ion batteries.

  20. N/S co-doped carbon derived from Cotton as high performance anode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Xiong, Jiawen; Pan, Qichang; Zheng, Fenghua; Xiong, Xunhui; Yang, Chenghao; Hu, Dongli; Huang, Chunlai

    2018-04-01

    Highly porous carbon with large surface areas is prepared using cotton as carbon sources which derived from discard cotton balls. Subsequently, the sulfur-nitrogen co-doped carbon was obtained by heat treatment the carbon in presence of thiourea and evaluated as Lithium-ion batteries anode. Benefiting from the S, N co-doping, the obtained S, N co-doped carbon exhibits excellent electrochemical performance. As a result, the as-prepared S, N co-doped carbon can deliver a high reversible capacity of 1101.1 mA h g-1 after 150 cycles at 0.2 A g-1, and a high capacity of 531.2 mA h g-1 can be observed even after 5000 cycles at 10.0 A g-1. Moreover, excellently rate capability also can be observed, a high capacity of 689 mA h g-1 can be obtained at 5.0 A g-1. This superior lithium storage performance of S, N co-doped carbon make it as a promising low-cost and sustainable anode for high performance lithium ion batteries.

  1. Rare-earth doped gadolinia based phosphors for potential multicolor and white light emitting deep UV LEDs.

    PubMed

    Bedekar, Vinila; Dutta, Dimple P; Mohapatra, M; Godbole, S V; Ghildiyal, R; Tyagi, A K

    2009-03-25

    Gadolinium oxide host and europium/dysprosium/terbium doped gadolinium oxide nanoparticles were synthesized using the sonochemical technique. Gadolinium oxide nanocrystals were also co-doped with total 2 mol% of Eu(3+)/Dy(3+),Eu(3+)/Tb(3+),Dy(3+)/Tb(3+), and also Eu(3+)/Dy(3+)/Tb(3+) ions, by the same method. The nanoparticles obtained were characterized using powder x-ray diffraction (XRD), transmission electron microscopy (TEM), and selected area electron diffraction (SAED) techniques. The size of the particles ranged from 15 to 30 nm. The triple doped samples showed multicolor emission on single wavelength excitation. The photoluminescence results were correlated with the lifetime data to get an insight into the luminescence and energy transfer processes taking place in the system. On excitation at 247 nm, the novel nanocrystalline Gd(2)O(3):RE (RE = Dy, Tb) phosphor resulted in having very impressive CIE chromaticity coordinates of x = 0.315 and y = 0.316, and a correlated color temperature of 6508 K, which is very close to standard daylight.

  2. Strongly enhanced oxygen ion transport through samarium-doped CeO 2 nanopillars in nanocomposite films

    DOE PAGES

    Yang, Sangmo; Lee, Shinbuhm; Jian, Jie; ...

    2015-10-08

    Enhancement of oxygen ion conductivity in oxides is important for low-temperature (<500 °C) operation of solid oxide fuel cells, sensors and other ionotronic devices. While huge ion conductivity has been demonstrated in planar heterostructure films, there has been considerable debate over the origin of the conductivity enhancement, in part because of the difficulties of probing buried ion transport channels. Here we create a practical geometry for device miniaturization, consisting of highly crystalline micrometre-thick vertical nanocolumns of Sm-doped CeO 2 embedded in supporting matrices of SrTiO 3. The ionic conductivity is higher by one order of magnitude than plain Sm-doped CeOmore » 2 films. By using scanning probe microscopy, we show that the fast ion-conducting channels are not exclusively restricted to the interface but also are localized at the Sm-doped CeO 2 nanopillars. This work offers a pathway to realize spatially localized fast ion transport in oxides of micrometre thickness.« less

  3. The EPR study of Mn(2+) ion doped DADT single crystal produced under high pressure and temperature.

    PubMed

    Ceylan, Ümit; Tapramaz, Recep

    2016-01-05

    An EPR study on Cu(2+) and VO(2+) doped di ammonium d-tartrate single crystals has been reported in previous papers, but the same host did not accept Mn(2+) ion at the same reaction conditions in previous trials. In this study EPR study of Mn(2+) ion doped di ammonium d tartrate single crystal, (DADT) [(NH4)2C4H4O6], produced in a reactor under high pressure and high temperature. The electronic transitions were determined by the optical absorption spectrum. Hyperfine splitting and g values of the Mn(2+) ion forming a complex in the lattice were measured from experimental spectra and spin-spin dipolar splitting parameters D and E were found by the spectrum simulation techniques. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Spectroscopic and ultrasonic investigations on structural characterization of borate glass specimen doped with transition metal ions.

    PubMed

    Sathish, K; Thirumaran, S

    2015-08-05

    The present work describes the glass samples of composition (x% V₂O₅-(80-x)% B₂O₃-20% Na₂CO₃) VBS glass system and (x%MnO₂-(80-x)% B₂O₃-20% Na₂CO₃) in MBS glass system with mol% ranging from x=3, 6, 9, 12, 15 and 18 in steps of 3 mol% are prepared by melt quenching technique. For these prepared glass systems, sound velocity (longitudinal and shear velocities) and density have been measured. The sound velocity (longitudinal and shear) was measured by using pulse-echo technique at 5 MHz. The XRD study was carried to out to ascertain the amorphous nature of the glass specimen. Using these measured values, the elastic moduli, Poisson's ratio, Debye temperature, acoustic impedance and thermal expansion coefficient of the two glass systems were evaluated. The elastic and mechanical properties of the prepared glass systems are analyzed from ultrasonic study and the structural characterization from spectroscopic study. The effects due to the doping of transition metal ions with borate have been discussed. In the V₂O₅ doped glass system,(VBS glass system) the sound velocity, density and elastic moduli, steeply increases after 12 mol% comparatively with MnO₂ doped glass system (VBS glass system). The present study critically observes the doping of V₂O₅ with borate enhances the strengthening of network linkage and hardening of the glassy network structure than MnO₂. The IR spectral analysis reveals depolymerization of the borate network and conversion of BO₃ or BO4 units with the formation of non-bridging oxygen. The FTIR spectral studies confirm the presence of various functional groups of the sample. FTIR spectrum of sample exhibits broad absorption bands indicating the wide distribution of borate structural units. The effect of Na₂CO₃, V₂O₅ and MnO₂ contents on the structures of borate glass is evaluated from the FTIR spectra. The topological aspects of the prepared glass samples are exhaustively reported from SEM micrographs

  5. Spectroscopic and ultrasonic investigations on structural characterization of borate glass specimen doped with transition metal ions

    NASA Astrophysics Data System (ADS)

    Sathish, K.; Thirumaran, S.

    2015-08-01

    The present work describes the glass samples of composition (x% V2O5-(80-x)% B2O3-20% Na2CO3) VBS glass system and (x% MnO2-(80-x)% B2O3-20% Na2CO3) in MBS glass system with mol% ranging from x = 3, 6, 9, 12, 15 and 18 in steps of 3 mol% are prepared by melt quenching technique. For these prepared glass systems, sound velocity (longitudinal and shear velocities) and density have been measured. The sound velocity (longitudinal and shear) was measured by using pulse-echo technique at 5 MHz. The XRD study was carried to out to ascertain the amorphous nature of the glass specimen. Using these measured values, the elastic moduli, Poisson's ratio, Debye temperature, acoustic impedance and thermal expansion coefficient of the two glass systems were evaluated. The elastic and mechanical properties of the prepared glass systems are analyzed from ultrasonic study and the structural characterization from spectroscopic study. The effects due to the doping of transition metal ions with borate have been discussed. In the V2O5 doped glass system, (VBS glass system) the sound velocity, density and elastic moduli, steeply increases after 12 mol% comparatively with MnO2 doped glass system (VBS glass system). The present study critically observes the doping of V2O5 with borate enhances the strengthening of network linkage and hardening of the glassy network structure than MnO2. The IR spectral analysis reveals depolymerization of the borate network and conversion of BO3 or BO4 units with the formation of non-bridging oxygen. The FTIR spectral studies confirm the presence of various functional groups of the sample. FTIR spectrum of sample exhibits broad absorption bands indicating the wide distribution of borate structural units. The effect of Na2CO3, V2O5 and MnO2 contents on the structures of borate glass is evaluated from the FTIR spectra. The topological aspects of the prepared glass samples are exhaustively reported from SEM micrographs.

  6. Ion engine propelled Earth-Mars cycler with nuclear thermal propelled transfer vehicle, volume 2

    NASA Technical Reports Server (NTRS)

    Meyer, Rudolf X.; Baker, Myles; Melko, Joseph

    1994-01-01

    The goal of this project was to perform a preliminary design of a long term, reusable transportation system between earth and Mars which would be capable of providing both artificial gravity and shelter from solar flare radiation. The heart of this system was assumed to be a Cycler spacecraft propelled by an ion propulsion system. The crew transfer vehicle was designed to be propelled by a nuclear-thermal propulsion system. Several Mars transportation system architectures and their associated space vehicles were designed.

  7. Studies of the Core Conditions of the Earth and Super-Earths Using Intense Ion Beams at FAIR

    SciT

    Tahir, N. A.; Neumayer, P.; Bagnoud, V.

    Using detailed numerical simulations, we present the design of an experiment that will generate samples of iron under extreme conditions of density and pressure believed to exist in the interior of the Earth and interior of extrasolar Earth-like planets. In the proposed experiment design, an intense uranium beam is used to implode a multilayered cylindrical target that consists of a thin Fe cylinder enclosed in a thick massive W shell. Such intense uranium beams will be available at the heavy-ion synchrotron, SIS100, at the Facility for Antiprotons and Ion Research (FAIR), at Darmstadt, which is under construction and will becomemore » operational in the next few years. It is expected that the beam intensity will increase gradually over a couple of years to its maximum design value. Therefore, in our studies, we have considered a wide range of beam parameters, from the initial beam intensity (“Day One”) to the maximum specified value. It is also worth noting that two different focal spot geometries have been used. In one case, a circular focal spot with a Gaussian transverse intensity distribution is considered, whereas in the other case, an annular focal spot is used. With these two beam geometries, one can access different parts of the Fe phase diagram. For example, heating the sample with a circular focal spot generates a hot liquid state, while an annular focal spot can produce a highly compressed liquid or a highly compressed solid phase depending on the beam intensity.« less

  8. N-doping effectively enhances the adsorption capacity of biochar for heavy metal ions from aqueous solution.

    PubMed

    Yu, Wenchao; Lian, Fei; Cui, Guannan; Liu, Zhongqi

    2018-02-01

    N-doping was successfully employed to improve the adsorption capacity of biochar (BC) for Cu 2+ and Cd 2+ by direct annealing of crop straws in NH 3 . The surface N content of BC increased more than 20 times by N-doping; meanwhile the content of oxidized-N was gradually diminished but graphitic-N was formed and increased with increasing annealing temperature and duration time. After N-doping, a high graphitic-N percentage (46.4%) and S BET (418.7 m 2 /g) can be achieved for BC. As a result, the N-doped BC exhibited an excellent adsorption capacity for Cu 2+ (1.63 mmol g -1 ) and Cd 2+ (1.76 mmol g -1 ), which was up to 4.0 times higher than that of the original BC. Furthermore, the adsorption performance of the N-doped BC remained stable even at acidic conditions. A positive correlation can be found between adsorption capacity with the graphitic N content on BC surface. The surface chemistry of N-doped BC before and after the heavy metal ions adsorption was carefully examined by XPS and FTIR techniques, which indicated that the adsorption mechanisms mainly included cation-π bonding and complexation with graphitic-N and hydroxyl groups of carbon surfaces. Copyright © 2017 Elsevier Ltd. All rights reserved.

  9. High-Level Heteroatom Doped Two-Dimensional Carbon Architectures for Highly Efficient Lithium-Ion Storage

    NASA Astrophysics Data System (ADS)

    Wang, Zhijie; Wang, Yanyan; Wang, Wenhui; Yu, Xiaoliang; Lv, Wei; Xiang, Bin; He, Yan-Bing

    2018-04-01

    In this work, high-level heteroatom doped two-dimensional hierarchical carbon architectures (H-2D-HCA) are developed for highly efficient Li-ion storage applications. The achieved H-2D-HCA possesses a hierarchical 2D morphology consisting of tiny carbon nanosheets vertically grown on carbon nanoplates and containing a hierarchical porosity with multiscale pore size. More importantly, the H-2D-HCA shows abundant heteroatom functionality, with sulfur (S) doping of 0.9 % and nitrogen (N) doping of as high as 15.5 %, in which the electrochemically active N accounts for 84 % of total N heteroatoms. In addition, the H-2D-HCA also has an expanded interlayer distance of 0.368 nm. When used as lithium-ion battery anodes, it shows excellent Li-ion storage performance. Even at a high current density of 5 A g-1, it still delivered a high discharge capacity of 329 mA h g-1 after 1000 cycles. First principle calculations verified that such unique microstructure characteristics and high-level heteroatom doping nature can enhance Li adsorption stability, electronic conductivity and Li diffusion mobility of carbon nanomaterials. Therefore, the H-2D-HCA could be promising candidates for next-generation LIB anodes.

  10. High-Level Heteroatom Doped Two-Dimensional Carbon Architectures for Highly Efficient Lithium-Ion Storage.

    PubMed

    Wang, Zhijie; Wang, Yanyan; Wang, Wenhui; Yu, Xiaoliang; Lv, Wei; Xiang, Bin; He, Yan-Bing

    2018-01-01

    In this work, high-level heteroatom doped two-dimensional hierarchical carbon architectures (H-2D-HCA) are developed for highly efficient Li-ion storage applications. The achieved H-2D-HCA possesses a hierarchical 2D morphology consisting of tiny carbon nanosheets vertically grown on carbon nanoplates and containing a hierarchical porosity with multiscale pore size. More importantly, the H-2D-HCA shows abundant heteroatom functionality, with sulfur (S) doping of 0.9% and nitrogen (N) doping of as high as 15.5%, in which the electrochemically active N accounts for 84% of total N heteroatoms. In addition, the H-2D-HCA also has an expanded interlayer distance of 0.368 nm. When used as lithium-ion battery anodes, it shows excellent Li-ion storage performance. Even at a high current density of 5 A g -1 , it still delivers a high discharge capacity of 329 mA h g -1 after 1,000 cycles. First principle calculations verifies that such unique microstructure characteristics and high-level heteroatom doping nature can enhance Li adsorption stability, electronic conductivity and Li diffusion mobility of carbon nanomaterials. Therefore, the H-2D-HCA could be promising candidates for next-generation LIB anodes.

  11. High-Level Heteroatom Doped Two-Dimensional Carbon Architectures for Highly Efficient Lithium-Ion Storage

    PubMed Central

    Wang, Zhijie; Wang, Yanyan; Wang, Wenhui; Yu, Xiaoliang; Lv, Wei; Xiang, Bin; He, Yan-Bing

    2018-01-01

    In this work, high-level heteroatom doped two-dimensional hierarchical carbon architectures (H-2D-HCA) are developed for highly efficient Li-ion storage applications. The achieved H-2D-HCA possesses a hierarchical 2D morphology consisting of tiny carbon nanosheets vertically grown on carbon nanoplates and containing a hierarchical porosity with multiscale pore size. More importantly, the H-2D-HCA shows abundant heteroatom functionality, with sulfur (S) doping of 0.9% and nitrogen (N) doping of as high as 15.5%, in which the electrochemically active N accounts for 84% of total N heteroatoms. In addition, the H-2D-HCA also has an expanded interlayer distance of 0.368 nm. When used as lithium-ion battery anodes, it shows excellent Li-ion storage performance. Even at a high current density of 5 A g−1, it still delivers a high discharge capacity of 329 mA h g−1 after 1,000 cycles. First principle calculations verifies that such unique microstructure characteristics and high-level heteroatom doping nature can enhance Li adsorption stability, electronic conductivity and Li diffusion mobility of carbon nanomaterials. Therefore, the H-2D-HCA could be promising candidates for next-generation LIB anodes. PMID:29686985

  12. Energetics of alkali and alkaline earth ion-exchanged zeolite A

    DOE PAGES

    Sun, Hui; Wu, Di; Liu, Kefeng; ...

    2016-06-30

    Alkali and alkaline earth ion-exchanged zeolite A samples were synthesized in aqueous exchange media. They were thoroughly studied by powder X-ray diffraction (XRD), electron microprobe (EMPA), thermogravimetric analysis and differential scanning calorimetry (TG-DSC), and high temperature oxide melt solution calorimetry. The hydration energetics and enthalpies of formation of these zeolite A materials from constituent oxides were determined. Specifically, the hydration level of zeolite A has a linear dependence on the average ionic potential ( Z/r) of the cation, from 0.894 (Rb-A) to 1.317 per TO 2 (Mg-A). The formation enthalpies from oxides (25 °C) range from –93.71 ± 1.77 (K-A)more » to –48.02 ± 1.85 kJ/mol per TO 2 (Li-A) for hydrated alkali ion-exchanged zeolite A, and from –47.99 ± 1.20 (Ba-A) to –26.41 ± 1.71 kJ/mol per TO 2 (Mg-A) for hydrated alkaline earth ion-exchanged zeolite A. As a result, the formation enthalpy from oxides generally becomes less exothermic as Z/r increases, but a distinct difference in slope is observed between the alkali and the alkaline earth series.« less

  13. Ion Composition and Energization in the Earth's Inner Magnetosphere and the Effects on Ring Current Buildup

    NASA Astrophysics Data System (ADS)

    Keika, K.; Kistler, L. M.; Brandt, P. C.

    2014-12-01

    In-situ observations and modeling work have confirmed that singly-charged oxygen ions, O+, which are of Earth's ionospheric origin, are heated/accelerated up to >100 keV in the magnetosphere. The energetic O+ population makes a significant contribution to the plasma pressure in the Earth's inner magnetosphere during magnetic storms, although under quiet conditions H+ dominates the plasma pressure. The pressure enhancements, which we term energization, are caused by adiabatic heating through earthward transport of source population in the plasma sheet, local acceleration in the inner magnetosphere and near-Earth plasma sheet, and enhanced ion supply from the topside ionosphere. The key issues regarding stronger O+ energization than H+ are non-adiabatic local acceleration, responsible for increase in O+ temperature, and more significant O+ supply than H+, responsible for increase in O+ density. Although several acceleration mechanisms and O+ supply processes have been proposed, it remains an open question what mechanism(s)/process(es) play the dominant role in stronger O+ energization. In this paper we summarize important spacecraft observations including those from Van Allen Probes, introduces the proposed mechanisms/processes that generate O+-rich energetic plasma population, and outlines possible scenarios of O+ pressure abundance in the Earth's inner magnetosphere.

  14. Venus, Earth, Mars: Comparative ion escape caused by the interaction with the solar wind

    NASA Astrophysics Data System (ADS)

    Barabash, Stas

    For the solar system planets the non-thermal atmospheric escape exceeds by far the Jean escape for particles heavier than helium. In this talk we consider only ion escape and compare the total ion escape rates for Venus, Earth, and Mars caused by the interaction with the solar wind. We review the most recent data on the escape rates based on measurements from Mars Express, Venus Express, and Cluster. The comparison of the available numbers show that despite large differences in the atmospheric masses between these three planets (a factor of 100 -200), different types of the interactions with the solar wind (magnetized and non-magnetized obstacles), the escape rates for Mars, Venus, and the Earth are within the range 1024 - 1025 s-1 . Surprisingly, the expected shielding of the Earth atmosphere by the intrinsic magnetic field is not as efficient as one may think. The reason for this is the non-thermal escape caused by the solar wind interaction is a energy -limited process. Indeed, normalizing the escape rates to the planet-dependent escape energy and power available in the solar wind results in the normalized escape rates deferring only on a factor between three planets. The larger Earth's magnetosphere intercepts and tunnels down to the ionosphere more energy from the solar wind than more compact interaction regions of non-magnetized planets.

  15. Ion-beam doping of GaAs with low-energy (100 eV) C + using combined ion-beam and molecular-beam epitaxy

    NASA Astrophysics Data System (ADS)

    Iida, Tsutomu; Makita, Yunosuke; Kimura, Shinji; Winter, Stefan; Yamada, Akimasa; Fons, Paul; Uekusa, Shin-ichiro

    1995-01-01

    A combined ion-beam and molecular-beam-epitaxy (CIBMBE) system has been developed. This system consists of an ion implanter capable of producing ions in the energy range of 30 eV-30 keV and conventional solid-source MBE. As a successful application of CIBMBE, low-energy (100 eV) carbon ion (C+) irradiation during MBE growth of GaAs was carried out at substrate temperatures Tg between 500 and 590 °C. C+-doped layers were characterized by low-temperature (2 K) photoluminescence (PL), Raman scattering, and van der Pauw measurements. PL spectra of undoped GaAs grown by CIBMBE revealed that unintentional impurity incorporation into the epilayer is extremely small and precise doping effects are observable. CAs acceptor-related emissions such as ``g,'' [g-g], and [g-g]β are observed and their spectra are significantly changed with increasing C+ beam current density Ic. PL measurements showed that C atoms were efficiently incorporated during MBE growth by CIBMBE and were optically well activated as an acceptor in the as-grown condition even for Tg as low as 500 °C. Raman measurement showed negligible lattice damage of the epilayer bombarded with 100 eV C+ with no subsequent heat treatment. These results indicate that contamination- and damage-free impurity doping without postgrowth annealing can be achieved by the CIBMBE method.

  16. Ion-beam doping of GaAs with low-energy (100 eV) C(+) using combined ion-beam and molecular-beam epitaxy

    NASA Astrophysics Data System (ADS)

    Lida, Tsutomu; Makita, Yunosuke; Kimura, Shinji; Winter, Stefan; Yamada, Akimasa; Fons, Paul; Uekusa, Shin-Ichiro

    1995-01-01

    A combined ion-beam and molecular-beam-epitaxy (CIBMBE) system has been developed. This system consists of an ion implanter capable of producing ions in the energy range of 30 eV - 30 keV and conventional solid-source MBE. As a successful application of CIBMBE, low-energy (100 eV) carbon ion (C(+)) irradiation during MBE growth of GaAs was carried out at substrate temperatures T(sub g) between 500 and 590 C. C(+)-doped layers were characterized by low-temperature (2 K) photoluminescence (PL), Raman scattering, and van der Pauw measurements. PL spectra of undoped GaAs grown by CIBMBE revealed that unintentional impurity incorporation into the epilayer is extremely small and precise doping effects are observable. C(sub As) acceptor-related emissions such as 'g', (g-g), and (g-g)(sub beta) are observed and their spectra are significantly changed with increasing C(+) beam current density I(sub c). PL measurements showed that C atoms were efficiently incorporated during MBE growth by CIBMBE and were optically well activated as an acceptor in the as-grown condition even for T(sub g) as low as 500 C. Raman measurement showed negligible lattice damage of the epilayer bombarded with 100 eV C(+) with no subsequent heat treatment. These results indicate that contamination- and damage-free impurity doping without postgrowth annealing can be achieved by the CIBMBE method.

  17. Biocompatibility of Mg Ion Doped Hydroxyapatite Films on Ti-6Al-4V Surface by Electrochemical Deposition.

    PubMed

    Lee, Kang; Choe, Han-Cheol

    2016-02-01

    In this study, we prepared magnesium (Mg) doped nano-phase hydroxyapatite (HAp) films on the TiO2 nano-network surface using electrochemical deposition method. Ti-6Al-4V ELI surface was anodized in 5 M NaOH solution at 0.3 A for 10 min. Nano-network TiO2 surface were formed by these anodization steps which acted as templates and anchorage for growth of the Mg doped HAp during subsequent pulsed electrochemical deposition process at 85 degrees C. The phase and morphologies of HAp deposits were influenced by the Mg ion concentration.

  18. Kinetic theory for the ion humps at the foot of the Earth's bow shock

    SciT

    Jovanovic, D.; Krasnoselskikh, V. V.

    2009-10-15

    The nonlinear kinetic theory is presented for the ion acoustic perturbations at the foot of the Earth's quasiperpendicular bow shock, that is characterized by weakly magnetized electrons and unmagnetized ions. The streaming ions, due to the reflection of the solar wind ions from the shock, provide the free energy source for the linear instability of the acoustic wave. In the fully nonlinear regime, a coherent localized solution is found in the form of a stationary ion hump, which is traveling with the velocity close to the phase velocity of the linear mode. The structure is supported by the nonlinearities comingmore » from the increased population of the resonant beam ions, trapped in the self-consistent potential. As their size in the direction perpendicular to the local magnetic field is somewhat smaller that the electron Larmor radius and much larger that the Debye length, their spatial properties are determined by the effects of the magnetic field on weakly magnetized electrons. These coherent structures provide a theoretical explanation for the bipolar electric pulses, observed upstream of the shock by Polar and Cluster satellite missions.« less

  19. Exploring high power, extreme wavelength operating potential of rare-earth-doped silica fiber

    NASA Astrophysics Data System (ADS)

    Zhou, Pu; Li, Ruixian; Xiao, Hu; Huang, Long; Zhang, Hanwei; Leng, Jinyong; Chen, Zilun; Xu, Jiangmin; Wu, Jian; Wang, Xiong

    2017-08-01

    Ytterbium-doped fiber laser (YDFL) and Thulium doped fiber laser (TDFL) have been two kinds of the most widely studied fiber laser in recent years. Although both silica-based Ytterbium-doped fiber and Thulium doped fiber have wide emission spectrum band (more than 200 nm and 400 nm, respectively), the operation spectrum region of previously demonstrated high power YDFL and TDFL fall into 1060-1100 nm and 1900-2050nm. Power scaling of YDFL and TDFL operates at short-wavelength or long-wavelength band, especially for extreme wavelength operation, although is highly required in a large variety of application fields, is quite challenging due to small net gain and strong amplified spontaneous emission (ASE). In this paper, we will present study on extreme wavelength operation of high power YDFL and TDFL in our group. Comprehensive mathematical models are built to investigate the feasibility of high power operation and propose effective technical methods to achieve high power operation. We have achieved (1) Diodepumped 1150nm long wavelength YDFL with 120-watt level output power (2) Diode-pumped 1178nm long wavelength YDFL operates at high temperature with 30-watt level output power (3) Random laser pumped 2153nm long wavelength TDFL with 20-watt level output power (4) Diode-pumped 1018nm short wavelength YDFL with a record 2 kilowatt output power is achieved by using home-made fiber combiner.

  20. Optical properties of zinc borotellurite glass doped with trivalent dysprosium ion

    NASA Astrophysics Data System (ADS)

    Ami Hazlin, M. N.; Halimah, M. K.; Muhammad, F. D.; Faznny, M. F.

    2017-04-01

    The zinc borotellurite doped with dysprosium oxide glass samples with chemical formula {[(TeO2) 0 . 7(B2O3) 0 . 3 ] 0 . 7(ZnO) 0 . 3 } 1 - x(Dy2O3)x (where x=0.01, 0.02, 0.03, 0.04 and 0.05 M fraction) were prepared by using conventional melt quenching technique. The structural and optical properties of the proposed glass systems were characterized by using X-ray diffraction (XRD) spectroscopy, Fourier Transform Infrared (FTIR) spectroscopy, and UV-VIS spectroscopy. The amorphous nature of the glass systems is confirmed by using XRD technique. The infrared spectra of the glass systems indicate three obvious absorption bands which are assigned to BO3 and TeO4 vibrational groups. Based on the absorption spectra obtained, the direct and indirect optical band gaps, as well as the Urbach energy were calculated. It is observed that both the direct and indirect optical band gaps increase with the concentration of Dy3+ ions. On the other hand, the Urbach energy is observed to decrease as the concentration of Dy3+ ions increases.

  1. Near-infrared quantum cutting in Yb3+ ion doped strontium vanadate

    NASA Astrophysics Data System (ADS)

    Sawala, N. S.; Bajaj, N. S.; Omanwar, S. K.

    2016-05-01

    The materials Sr3-x(VO4)2:xYb were successfully synthesized by co-precipitation method varying the concentration of Yb3+ ions from 0 to 0.06 mol. It was characterize by powder X-ray powder diffraction (XRD) and surface morphology was studied by scanning electronic microscope (SEM). The photoluminescence (PL) properties were studied by spectrophotometers in near infra red (NIR) and ultra violet visible (UV-VIS) region. The Yb3+ ion doped tristrontium vanadate (Sr3(VO4)2) phosphors that can convert a photon of UV region (349 nm) into photons of NIR region (978, 996 and 1026 nm). Hence this phosphor could be used as a quantum cutting (QC) luminescent convertor in front of crystalline silicon solar cell (c-Si) panels to reduce thermalization loss due to spectral mismatch of the solar cells. The theoretical value of quantum efficiency (QE) was calculated from steady time decay measurement and the maximum efficiency approached up to 144.43%. The Sr(3-x) (VO4)2:xYb can be potentiality used for betterment of photovoltaic (PV) technology.

  2. Spectroscopic investigations on Pr3+ ions doped lead telluro-borate glasses for photonic applications

    NASA Astrophysics Data System (ADS)

    Suthanthirakumar, P.; Mariyappan, M.; Marimuthu, K.

    2018-04-01

    A new series of Lead telluro-borate glasses doped with different concentrations of Pr3+ ions (xPLTB) were prepared by melt quenching technique and their structural and spectroscopic properties were investigated by recording XRD, FTIR, optical absorption and luminescence spectral measurements. XRD measurements confirm the amorphous nature and the FTIR spectra reveal the presence of different vibrational modes of borate and tellurite networks in the prepared glasses. The bonding parameter values (δ) obtained from the absorption band positions indicates that the bonding between Pr3+ ions and their surrounding ligands is of ionic in nature. The optical band gap (Eopt) corresponding to the direct and indirect allowed transitions were determined with the framework of tauc's plot. From the luminescence spectra, important radiative parameters such as stimulated emission cross-section (σPE) , branching ratios (βR) and radiative lifetime (τR) were calculated for the dominant emission transition 3P0→3H4 (blue) in order to suggest the suitability of the studied glasses for suitable photonic applications.

  3. Evidence for solar wind origin of energetic heavy ions in the earth's radiation belt

    NASA Technical Reports Server (NTRS)

    Hovestadt, D.; Klecker, B.; Scholer, M.; Gloeckler, G.; Ipavich, F. M.; Fan, C. Y.; Fisk, L. A.; Ogallagher, J. J.

    1978-01-01

    Analysis of data from our energetic ion composition experiment on ISEE-1 has revealed the presence of substantial fluxes of carbon, oxygen, and heavier ions above 400 keV/nucleon at L values between approximately 2.5 and 4 earth radii. The measured C/O ratio varies systematically from 1.3 at 450 keV/nucleon to 4.1 at 1.3 MeV/nucleon, and no iron is observed above 200 keV/nucleon. These results provide strong evidence for a solar wind origin for energetic ions in the outer radiation belt. The absence of iron and the increase of the carbon-to-oxygen ratio with energy suggest that the condition for the validity of the first adiabatic invariant may have a strong influence on the trapping of these particles.

  4. Electromagnetic Ion Cyclotron Waves Detected by Kaguya and Geotail in the Earth's Magnetotail

    NASA Astrophysics Data System (ADS)

    Nakagawa, Tomoko; Nishino, Masaki N.; Tsunakawa, Hideo; Takahashi, Futoshi; Shibuya, Hidetoshi; Shimizu, Hisayoshi; Matsushima, Masaki; Saito, Yoshifumi

    2018-02-01

    Narrowband electromagnetic ion cyclotron waves first discovered by the Apollo 15 and 16 Lunar Surface Magnetometers were surveyed in the magnetic field data obtained by the Kaguya satellite at an altitude of ˜100 km above the Moon in the tail lobe and plasma sheet boundary layer of the Earth's magnetosphere. The frequencies of the waves were typically 0.7 times the local proton cyclotron frequency, and 75% of the waves were left hand polarized with respect to the background magnetic field. They had a significant compressional component and comprised several discrete packets. They were detected on the dayside, nightside, and above the terminator of the Moon, irrespective of the lunar magnetic anomaly, or the magnetic connection to the lunar surface. The waves with the same characteristics were detected by Geotail in the absence of the Moon in the magnetotail. The most likely energy source of the electromagnetic ion cyclotron waves is the ring beam ions in the plasma sheet boundary layer.

  5. Investigation of the Transport of Solar Ions Through the Earth's Magnetosphere

    NASA Technical Reports Server (NTRS)

    Lennartsson, O. W.; Evans, David (Technical Monitor)

    2000-01-01

    The objective of this study has been to infer, by statistical means, the most probable mode of entry of solar wind plasma into Earth's magnetotail, using a particular set of archived data from the Lockheed Plasma Composition Experiment on the International Sun-Earth Explorer One (ISEE-1) satellite, jointly sponsored by the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA) in the 1970's and 80's. Despite their considerable age, the Lockheed ISEE-1 data are still, at the time of this report, the only substantial ion composition data in the sub-keV to keV energy range available from the magnetotail beyond 9 R(sub E), because of various technical problems with ion mass spectrometers on later missions, and are therefore a unique source of information about the mixing of solar and terrestrial origin plasmas in the tail, within the ISEE-1 apogee of almost 23 R(sub E). The entire set of archived data used in this study, covering the 4.5 years of operation of the instrument and comprising not only tail measurements but also data from the inner magnetosphere as well as data from outside the magnetopause, is now available to the public via the WorldWideWeb at the address: http://cis.spasci.com/ISEE_ions The fundamental assumption of this and other studies of magnetosphere ion composition is that He++ and O+ ions are virtually certain "tags" of solar and terrestrial origins, respectively. This is an assumption with strong theoretical basis and it is corroborated by observational evidence, including the often substantial differences between the velocity distribution functions of those two species. The H+ ions can have a dual origin, in principle, but the close resemblance in the ISEE-1 data between the dynamics of H+ and He++ ions indicates a predominantly solar origin of the H+ ions in the tail, at least. By the same token, the usually minor He+ ions are probably almost entirely of terrestrial origin, because of their similarity to the O

  6. High charge state carbon and oxygen ions in Earth's equatorial quasi-trapping region

    NASA Technical Reports Server (NTRS)

    Christon, S. P.; Hamilton, D. C.; Gloeckler, G.; Eastmann, T. E.

    1994-01-01

    Observations of energetic (1.5 - 300 keV/e) medium-to-high charge state (+3 less than or equal to Q less than or equal to +7) solar wind origin C and O ions made in the quasi-trapping region (QTR) of Earth's magnetosphere are compared to ion trajectories calculated in model equatorial magnetospheric magnetic and electric fields. These comparisons indicate that solar wind ions entering the QTR on the nightside as an energetic component of the plasma sheet exit the region on the dayside, experiencing little or no charge exchange on the way. Measurements made by the CHarge Energy Mass (CHEM) ion spectrometer on board the Active Magnetospheric Particle Tracer Explorer/Charge Composition Explorer (AMPTE/CCE) spacecraft at 7 less than L less than 9 from September 1984 to January 1989 are the source of the new results contained herein: quantitative long-term determination of number densities, average energies, energy spectra, local time distributions, and their variation with geomagnetic disturbance level as indexed by Kp. Solar wind primaries (ions with charge states unchanged) and their secondaries (ions with generally lower charge states produced from primaries in the magnetosphere via charge exchange)are observed throughout the QTR and have distinctly different local time variations that persist over the entire 4-year analysis interval. During Kp larger than or equal to 3 deg intervals, primary ion (e.g., O(+6)) densities exhibit a pronounced predawn maximum with average energy minimum and a broad near-local-noon density minimum with average energy maximum. Secondary ion (e.g., O(+5)) densities do not have an identifiable predawn peak, rather they have a broad dayside maximum peaked in local morning and a nightside minimum. During Kp less than or equal to 2(-) intervals, primary ion density peaks are less intense, broader in local time extent, and centered near midnight, while secondary ion density local time variations diminish. The long-time-interval baseline helps

  7. Dielectric and nonlinear current-voltage characteristics of rare-earth doped CaCu3Ti4O12 ceramics

    NASA Astrophysics Data System (ADS)

    Liu, Laijun; Fang, Liang; Huang, Yanmin; Li, Yunhua; Shi, Danping; Zheng, Shaoying; Wu, Shuangshuang; Hu, Changzheng

    2011-11-01

    CaCu3Ti4O12 (CCTO) ceramics doped with rare earth (RE) oxides, including Y2O3, La2O3, Eu2O3, and Gd2O3, were prepared by the traditional solid-state reaction method in order to investigate the effect of RE oxide dopants on the electrical properties as a varistor. The phase identification and morphology of the ceramics were investigated by x-ray diffraction (XRD) and scanning electron microscope (SEM), respectively. A high voltage measuring unit and precision impedance analyzer were used to determine the nonohmic (J-E) behaviors and measure the dielectric properties and impedance spectroscopy of the ceramics, respectively. The results showed that RE oxides enhanced greatly the breakdown electric flied but reduced the nonlinear coefficient and the mean grain size of CCTO ceramics. There was a good linear relationship between ln J and E1/2, which demonstrated that the Schottky barrier should exist at the grain boundary. A double Schottky barrier model composed of a depletion layer and a negative charge sheet was proposed, analogous to the barrier model for ZnO varistors. The depletion layer width determined by diffusion distance of RE ions and the effective surface states played important roles on the electrical properties of the ceramics.

  8. Enhanced Fe dispersion via "pinning" effect of thiocyanate ion on ferric ion in Fe-N-S-doped catalyst as an excellent oxygen reduction reaction electrode

    NASA Astrophysics Data System (ADS)

    Shu, Chengyong; Chen, Yuanzhen; Yang, Xiao-Dong; Liu, Yan; Chong, Shaokun; Fang, Yuan; Liu, Yongning; Yang, Wei-Hua

    2018-02-01

    In this study, by using thiocyanate as an iron ion dispersing agent, the pinning effect of thiocyanate ion (SCN-) enables the high dispersion of Fe3+ in a nitrogen-doped carbon polymer and significantly promotes ORR catalysis in both acidic and alkaline media. It shows 47.3 A g-1 kinetic ORR current density in 0.1 M H2SO4 solution at 0.8 V vs. RHE. In addition, SCN- can dope into the base material and modify the surface of catalysts, which generates strong cyanide N functional groups. Additionally, it also has a higher BET surface area and more uniform granularity, which accounts for the enhancement in mass transport.

  9. Formation of Hierarchical Cu-Doped CoSe2 Microboxes via Sequential Ion Exchange for High-Performance Sodium-Ion Batteries.

    PubMed

    Fang, Yongjin; Yu, Xin-Yao; Lou, Xiong Wen David

    2018-04-06

    Electrode materials based on electrochemical conversion reactions have received considerable interest for high capacity anodes of sodium-ion batteries. However, their practical application is greatly hindered by the poor rate capability and rapid capacity fading. Tuning the structure at nanoscale and increasing the conductivity of these anode materials are two effective strategies to address these issues. Herein, a two-step ion-exchange method is developed to synthesize hierarchical Cu-doped CoSe 2 microboxes assembled by ultrathin nanosheets using Co-Co Prussian blue analogue microcubes as the starting material. Benefitting from the structural and compositional advantages, these Cu-doped CoSe 2 microboxes with improved conductivity exhibit enhanced sodium storage properties in terms of good rate capability and excellent cycling performance. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Spectral engineering of optical fiber through active nanoparticle doping

    NASA Astrophysics Data System (ADS)

    Lindstrom-James, Tiffany

    The spectral engineering of optical fiber is a method of intentional doping of the core region in order to absorb/emit specific wavelengths of light therby providing enhanced performance over current fibers. Efforts here focused on developing an understanding of optically active nanoparticles based on alkaline earth fluorides that could be easily and homogeneously incorporated into the core of a silica based optical fiber preform and result in efficient and tailorable spectral emissions. Doped and undoped calcium, strontium and barium fluoride nanoparticles were successfully synthesized and characterized for their physical, chemical, and optical behavior. Distinct spectroscopic differences as a result of different host materials, varying rare earth doping levels and processing conditions, indicated the ability to influence the spectral behavior of the doped nanoparticle. By using photoluminescence to predict diffusion behavior, the application of a simple one dimensional model for diffusion provided a method for predicting the diffusion coefficient of europium ions in alkaline earth fluorides with order of magnitude accuracy. Modified chemical vapor deposition derived silica preforms were individually solution doped with europium doped alkaline earth fluoride nanoparticles. By using the rare earth doped alkaline earth fluoride nanoparticles as the dopant materials in the core of optical fiber preforms, the resultant optical properties of the glass were significantly influenced by their presence in the core. The incorporation of these rare earth doped alkaline earth fluoride nanoparticles was found to significantly influence the local chemical and structural environment about the rare earth ion, demonstrated homogeneity and uniform distribution of the rare earth dopant and resulted in specifically unique spectral behavior when compared to conventional doping methods. A more detailed structural model of the doped core glass region has been developed based on the

  11. Three-dimensional endothelial cell morphogenesis under controlled ion release from copper-doped phosphate glass.

    PubMed

    Stähli, Christoph; James-Bhasin, Mark; Nazhat, Showan N

    2015-02-28

    Copper ions represent a promising angiogenic agent but are associated with cytotoxicity at elevated concentrations. Phosphate-based glasses (PGs) exhibit adjustable dissolution properties and allow for controlled ion release. This study examined the formation of capillary-like networks by SVEC4-10 endothelial cells (ECs) seeded in a three-dimensional (3D) type I collagen hydrogel matrix mixed with PG particles of the formulation 50P2O5-30CaO-(20-x)Na2O-xCuO (x=0 and 10 mol%). Copper and total phosphorus release decreased over time and was more sustained in the case of 10% CuO PG. Moreover, increasing the concentration of 10% CuO PG in collagen substantially delayed dissolution along with preferential release of copper. A 3D morphometric characterization method based on confocal laser scanning microscopy image stacks was developed in order to quantify EC network length, connectivity and branching. Network length was initially reduced in a concentration-dependent fashion by 10% CuO PG and, to a lesser extent, by 0% CuO PG, but reached values identical to the non-PG control by day 5 in culture. This reduction was attributed to a PG-mediated decrease in cell metabolic activity while cell proliferation as well as network connectivity and branching were independent of PG content. Gene expression of matrix metalloproteinases (MMP)-1 and -2 was up-regulated by PGs, indicating that MMPs did not play a critical role in network growth. The relationship between ion release and EC morphogenesis in 3D provided in this study is expected to contribute to an ultimately successful pro-angiogenic application of CuO-doped PGs. Copyright © 2015 Elsevier B.V. All rights reserved.

  12. Modulation of Crystal Surface and Lattice by Doping: Achieving Ultrafast Metal-Ion Insertion in Anatase TiO2.

    PubMed

    Wang, Hsin-Yi; Chen, Han-Yi; Hsu, Ying-Ya; Stimming, Ulrich; Chen, Hao Ming; Liu, Bin

    2016-10-26

    We report that an ultrafast kinetics of reversible metal-ion insertion can be realized in anatase titanium dioxide (TiO 2 ). Niobium ions (Nb 5+ ) were carefully chosen to dope and drive anatase TiO 2 into very thin nanosheets standing perpendicularly onto transparent conductive electrode (TCE) and simultaneously construct TiO 2 with an ion-conducting surface together with expanded ion diffusion channels, which enabled ultrafast metal ions to diffuse across the electrolyte/solid interface and into the bulk of TiO 2 . To demonstrate the superior metal-ion insertion rate, the electrochromic features induced by ion intercalation were examined, which exhibited the best color switching speed of 4.82 s for coloration and 0.91 s for bleaching among all reported nanosized TiO 2 devices. When performed as the anode for the secondary battery, the modified TiO 2 was capable to deliver a highly reversible capacity of 61.2 mAh/g at an ultrahigh specific current rate of 60 C (10.2 A/g). This fast metal-ion insertion behavior was systematically investigated by the well-controlled electrochemical approaches, which quantitatively revealed both the enhanced surface kinetics and bulk ion diffusion rate. Our study could provide a facile methodology to modulate the ion diffusion kinetics for metal oxides.

  13. Electrochemical Properties of Boron-Doped Fullerene Derivatives for Lithium-Ion Battery Applications.

    PubMed

    Sood, Parveen; Kim, Ki Chul; Jang, Seung Soon

    2018-03-19

    The high electron affinity of fullerene C 60 coupled with the rich chemistry of carbon makes it a promising material for cathode applications in lithium-ion batteries. Since boron has one electron less than carbon, the presence of boron on C 60 cages is expected to generate electron deficiency in C 60 , and thereby to enhance its electron affinity. By using density functional theory (DFT), we studied the redox potentials and electronic properties of C 60 and C 59 B. We have found that doping C 60 with one boron atom results in a substantial increase in redox potential from 2.462 V to 3.709 V, which was attributed to the formation of an open shell system. We also investigated the redox and electronic properties of C 59 B functionalized with various redox-active oxygen containing functional groups (OCFGs). For the combination of functionalization with OCFGs and boron doping, it is found that the enhancement of redox potential is reduced, which is mainly attributed to the open shell structure being changed to a closed-shell one. Nevertheless, the redox potentials are still higher than that of pristine C 60 . From the observation that the lowest unoccupied molecular orbital of closed-shell OCFG- functionalized C 59 B is correlated well with the redox potential, it was confirmed that the spin state is crucial to be considered to understand the relationship between electronic structure and redox properties. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Strain tunable magnetic properties of 3d transition-metal ion doped monolayer MoS2: A first-principles study

    NASA Astrophysics Data System (ADS)

    Zhu, Yupeng; Liang, Xiao; Qin, Jun; Deng, Longjiang; Bi, Lei

    2018-05-01

    In this article, a systematic study on the magnetic properties and strain tunability of 3d transition metal ions (Mn, Fe, Co, Ni) doped MoS2 using first-principles calculations is performed. Antiferromagnetic coupling is observed between Mn, Fe ions and the nearest neighbor Mo ions; whereas ferromagnetic coupling is observed in Co and Ni systems. It is also shown that by applying biaxial tensile strain, a significant change of the magnetic moment is observed in all transition metal doped MoS2 materials with a strain threshold. The changes of total magnetic moment have different mechanisms for different doping systems including an abrupt change of the bond lengths, charge transfer and strain induced structural anisotropy. These results demonstrate applying strain as a promising method for tuning the magnetic properties in transition metal ion doped monolayer MoS2.

  15. Ion beam irradiation of lanthanum and thorium-doped yttrium titanates

    NASA Astrophysics Data System (ADS)

    Lian, J.; Zhang, F. X.; Peters, M. T.; Wang, L. M.; Ewing, R. C.

    2007-05-01

    Y2Ti2O7 pyrochlores doped with La have been sintered at 1373 K for 12 h with the designed compositions of the (LaxY1-x)2Ti2O7 system (x = 0, 0.08, 0.5, and 1), and the phase compositions were analyzed by X-ray diffraction. Limited amounts of La were incorporated into yttrium titanate pyrochlore structure for La-doped samples; while, the end member composition of La2Ti2O7 formed a layered perovskite structure. Ion beam-induced amorphization occurred for all compositions in the (LaxY1-x)2Ti2O7 binary under 1 MeV Kr2+ irradiation at room temperature, and the critical amorphization dose decreased with increasing amounts of La3+. The critical amorphization temperatures for Y2Ti2O7, (La0.162Y0.838)2Ti2O7 and La2Ti2O7 were determined to be ∼780, 890 and 920 K, respectively. Th4+ and Fe3+-doped yttrium titanate pyrochlores were synthesized at 1373 K by sintering Y2Ti2O7 with (ThO2 + Fe2O3). Pyrochlore structures and the chemical compositions were primarily identified by the X-ray diffraction and energy dispersive X-ray (EDX) measurements. The lattice parameter and the critical amorphization dose (1 MeV Kr2+ at room temperature) increase for yttrium titanate pyrochlores with the addition of Th. The increasing 'resistance' to amorphization with less La and greater Th and Fe contents for (Y1-xLax)2Ti2O7 and Y2Ti2O7-Fe2O3-ThO2 systems, respectively, are consistent with the changes in the average ionic radius ratio at the A-sites and B-sites. These results suggest that the addition of lanthanides and actinides (e.g., Th, U, or Pu) will affect the structural stability, as well as the radiation response behavior of the pyrochlore structure-type.

  16. Rare-earth doped transparent ceramics for spectral filtering and quantum information processing

    NASA Astrophysics Data System (ADS)

    Kunkel, Nathalie; Ferrier, Alban; Thiel, Charles W.; Ramírez, Mariola O.; Bausá, Luisa E.; Cone, Rufus L.; Ikesue, Akio; Goldner, Philippe

    2015-09-01

    Homogeneous linewidths below 10 kHz are reported for the first time in high-quality Eu3+ doped Y 2O3 transparent ceramics. This result is obtained on the 7F0→5D0 transition in Eu3+ doped Y 2O3 ceramics and corresponds to an improvement of nearly one order of magnitude compared to previously reported values in transparent ceramics. Furthermore, we observed spectral hole lifetimes of ˜15 min that are long enough to enable efficient optical pumping of the nuclear hyperfine levels. Additionally, different Eu3+ concentrations (up to 1.0%) were studied, resulting in an increase of up to a factor of three in the peak absorption coefficient. These results suggest that transparent ceramics can be useful in applications where narrow and deep spectral holes can be burned into highly absorbing lines, such as quantum information processing and spectral filtering.

  17. Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO₃ thin films.

    PubMed

    Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

    2013-05-22

    Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different.

  18. A confined "microreactor" synthesis strategy to three dimensional nitrogen-doped graphene for high-performance sodium ion battery anodes

    NASA Astrophysics Data System (ADS)

    Li, Jiajie; Zhang, Yumin; Gao, Tangling; Han, Jiecai; Wang, Xianjie; Hultman, Benjamin; Xu, Ping; Zhang, Zhihua; Wu, Gang; Song, Bo

    2018-02-01

    In virtue of abundant sodium resources, sodium ion batteries (SIBs) have been regarded as one of the most promising alternatives for large-scale energy storage applications. However, the absence of a suitable anode material makes it difficult to realize these applications. Here, we demonstrate an effective synthesis strategy of using a "microreactor" consisting of melamine fiber (inside) and graphene oxide (GO, outside) to fabricate three dimensional (3D) nitrogen doped (N-doped) graphene as high-performance anode materials for sodium ion batteries. Through a controlled pyrolysis, the inside melamine fiber and the outside GO layer has been converted into N-doped graphene and reduced graphene oxide (r-GO) respectively, and thus the "microreactor" is transformed into interconnected 3D N-doped graphene structures. Such highly desired 3D graphene structures show reversible sodium storage capacities up to ∼305 mA h g-1 after 500 cycles at a current density of 0.2 A g-1 and promising long cycling stability with a stable capacity of ∼198 mA h g-1 at 5 A g-1 after 5000 cycles. The high capacity and superior durability in combination with the facile synthesis procedure of the 3D graphene structure make it a promising anode material for SIBs and other energy storage applications.

  19. Self-propagating high-temperature synthesis and luminescent properties of ytterbium doped rare earth (Y, Sc, Lu) oxides nanopowders

    NASA Astrophysics Data System (ADS)

    Permin, D. A.; Novikova, A. V.; Balabanov, S. S.; Gavrishchuk, E. M.; Kurashkin, S. V.; Savikin, A. P.

    2018-04-01

    This paper describes a comparative study of structural and luminescent properties of 5%Yb-doped yttrium, scandium, and lutetium oxides (Yb:RE2O3) powders and ceramics fabricated by self-propagating high-temperature synthesis. According to X-ray diffractometry and electron microscopy the chosen method ensures preparation of low-agglomerated cubic Ctype crystal structured powders at one step. No crucial differences in luminescence spectra were found the Yb:RE2O3 powders and ceramics. It was shown that the emission lifetimes of the Yb:RE2O3 powders are lowered by crystal structure defects, while its values for ceramics samples are compared to that of monocrystals and more influenced by rare earth impurities.

  20. Effect of temperature and rare-earth doping on charge-carrier mobility in indium-monoselenide crystals

    SciT

    Abdinov, A. Sh., E-mail: abdinov-axmed@yandex.ru; Babayeva, R. F., E-mail: Babaeva-Rena@yandex.ru; Amirova, S. I.

    2013-08-15

    In the temperature range T = 77-600 K, the dependence of the charge-carrier mobility ({mu}) on the initial dark resistivity is experimentally investigated at 77 K ({rho}d{sub 0}), as well as on the temperature and the level (N) of rare-earth doping with such elements as gadolinium (Gd), holmium (Ho), and dysprosium (Dy) in n-type indium-monoselenide (InSe) crystals. It is established that the anomalous behavior of the dependences {mu}(T), {mu}({rho}d{sub 0}), and {mu}(N) found from the viewpoint of the theory of charge-carrier mobility in crystalline semiconductors is related, first of all, to partial disorder in indium-monoselenide crystals and can be attributedmore » to the presence of random drift barriers in the free energy bands.« less

  1. GYROSURFING ACCELERATION OF IONS IN FRONT OF EARTH's QUASI-PARALLEL BOW SHOCK

    SciT

    Kis, Arpad; Lemperger, Istvan; Wesztergom, Viktor

    2013-07-01

    It is well known that shocks in space plasmas can accelerate particles to high energies. However, many details of the shock acceleration mechanism are still unknown. A critical element of shock acceleration is the injection problem; i.e., the presence of the so called seed particle population that is needed for the acceleration to work efficiently. In our case study, we present for the first time observational evidence of gyroresonant surfing acceleration in front of Earth's quasi-parallel bow shock resulting in the appearance of the long-suspected seed particle population. For our analysis, we use simultaneous multi-spacecraft measurements provided by the Clustermore » spacecraft ion (CIS), magnetic (FGM), and electric field and wave instrument (EFW) during a time period of large inter-spacecraft separation distance. The spacecraft were moving toward the bow shock and were situated in the foreshock region. The results show that the gyroresonance surfing acceleration takes place as a consequence of interaction between circularly polarized monochromatic (or quasi-monochromatic) transversal electromagnetic plasma waves and short large amplitude magnetic structures (SLAMSs). The magnetic mirror force of the SLAMS provides the resonant conditions for the ions trapped by the waves and results in the acceleration of ions. Since wave packets with circular polarization and different kinds of magnetic structures are very commonly observed in front of Earth's quasi-parallel bow shock, the gyroresonant surfing acceleration proves to be an important particle injection mechanism. We also show that seed ions are accelerated directly from the solar wind ion population.« less

  2. Stable silicon/3D porous N-doped graphene composite for lithium-ion battery anodes with self-assembly

    NASA Astrophysics Data System (ADS)

    Tang, Xiaofu; Wen, Guangwu; Song, Yan

    2018-04-01

    We fabricate a novel 3D N-doped graphene/silicon composite for lithium-ion battery anodes, with Si nanoparticles uniformly dispersed and thoroughly embedded in the N-doped graphene matrix. The favorable structure of the composite results in a BET surface area and an average mesopore diameter of 189.2 m2 g-1 and 3.82 nm, respectively. The composite delivers reversible capacities as high as 1132 mA h g-1 after 100 cycles under a current of 5 A g-1 and 1017 mA h g-1 after 200 cycles at 1 A g-1, and exhibits an improved rate capability. The present approach shows promise for the preparation of other high-performance anode materials for lithium-ion batteries.

  3. Spectroscopic properties of Sm3 + ions doped Alkaliborate glasses for photonics applications

    NASA Astrophysics Data System (ADS)

    Nagaraj, R.; Suthanthirakumar, P.; Vijayakumar, R.; Marimuthu, K.

    2017-10-01

    A new series of Sm3 + doped alkaliborate glasses have been prepared by melt quenching technique and their structural and spectroscopic properties were analysed employing XRD, FTIR, optical absorption, photoluminescence and decay spectral measurements in order to explore their suitability for photonic applications. The amorphous nature have been confirmed through XRD analysis and the FTIR spectra reveal the presence of fundamental stretching and bending vibrations of the borate networks in the prepared glasses. From the absorption peak positions, bonding parameter (δ) values were calculated to examine the nature of the metal-ligand bond. The optical band gap (Eopt) corresponds to the direct and indirect allowed transitions and the Urbach energies (ΔE) were calculated from the absorption spectra to understand the electronic band structure of the studied glasses. The Judd-Ofelt (JO) intensity parameters Ωλ (λ = 2, 4 and 6) were determined to explore the symmetry of the ligand environment around the Sm3 + ions in the studied glasses. The luminescence spectra exhibit four emission bands in the visible region due to the 4G5/2 → 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions. The radiative parameters such as transition probability (A), stimulated emission cross-section (σPE), branching ratios (βR) and radiative lifetime (τR) have been determined from the luminescence spectra using JO theory to ensure the suitability of the studied glasses for optoelectronic applications. The luminescence spectra were characterized through CIE 1931 chromaticity diagram to examine the dominant emission color of the studied glasses. The lifetime values of the Sm3 + doped studied glasses pertaining to the 4G5/2 excited level have been determined through decay curve measurements and the non-exponential decay curves were fitted to the Inokuti-Hirayama model to analyze the energy transfer mechanism between the nearby Sm3 + ions. The obtained results were discussed and compared with the

  4. Comparative study of ion cyclotron waves at Mars, Venus and Earth

    NASA Astrophysics Data System (ADS)

    Wei, H. Y.; Russell, C. T.; Zhang, T. L.; Blanco-Cano, X.

    2011-08-01

    Ion cyclotron waves are generated in the solar wind when it picks up freshly ionized planetary exospheric ions. These waves grow from the free energy of the highly anisotropic distribution of fresh pickup ions, and are observed in the spacecraft frame with left-handed polarization and a wave frequency near the ion's gyrofrequency. At Mars and Venus and in the Earth's polar cusp, the solar wind directly interacts with the planetary exospheres. Ion cyclotron waves with many similar properties are observed in these diverse plasma environments. The ion cyclotron waves at Mars indicate its hydrogen exosphere to be extensive and asymmetric in the direction of the interplanetary electric field. The production of fast neutrals plays an important role in forming an extended exosphere in the shape and size observed. At Venus, the region of exospheric proton cyclotron wave production may be restricted to the magnetosheath. The waves observed in the solar wind at Venus appear to be largely produced by the solar-wind-Venus interaction, with some waves at higher frequencies formed near the Sun and carried outward by the solar wind to Venus. These waves have some similarity to the expected properties of exospherically produced proton pickup waves but are characterized by magnetic connection to the bow shock or by a lack of correlation with local solar wind properties respectively. Any confusion of solar derived waves with exospherically derived ion pickup waves is not an issue at Mars because the solar-produced waves are generally at much higher frequencies than the local pickup waves and the solar waves should be mostly absorbed when convected to Mars distance as the proton cyclotron frequency in the plasma frame approaches the frequency of the solar-produced waves. In the Earth's polar cusp, the wave properties of ion cyclotron waves are quite variable. Spatial gradients in the magnetic field may cause this variation as the background field changes between the regions in which

  5. The Role of the Ion Microprobe in Solid-Earth Geochemistry

    NASA Astrophysics Data System (ADS)

    Hauri, E. H.

    2002-12-01

    Despite the early success of the electron microprobe in taking petrology to the micron scale, and the widespread use of mass spectrometers in geochemistry and geochronology, it was not until the mid-1970s that the ion microprobe came into its own as an in situ analytical tool in the Earth sciences. Despite this inauspicious beginning, secondary ion mass spectrometry (SIMS) was widely advertised as a technology that would eventually eclipse thermal ion mass spectrometry (TIMS) in isotope geology. However this was not to happen. While various technical issues in SIMS such as interferences and matrix effects became increasingly clear, an appreciation grew for the complimentary abilities of SIMS and TIMS that, even with the advent of ICP-MS, continues to this day. Today the ion microprobe is capable of abundance measurements in the parts-per-billion range across nearly the entire periodic table, and SIMS stable isotope data quality is now routinely crossing the 1 per mil threshold, all at the micron scale. Much of this success is due to the existence of multi-user community facilities for SIMS research, and the substantial efforts of interested scientists to understand the fundamentals of sputtered ion formation and their application to geochemistry. Recent discoveries of evidence for the existence of ancient crust and oceans, the emergence of life on Earth, the large-scale cycling of surficial materials into the deep Earth, and illumination of fundamental high-pressure phenomena have all been made possible by SIMS, and these (and many more) discoveries owe a debt to the vision of creating and supporting multi-user community facilities for SIMS. The ion microprobe remains an expensive instrument to purchase and maintain, yet it is also exceedingly diverse in application. Major improvements in SIMS, indeed in all mass spectrometry, are visible on the near horizon. Yet the geochemical community cannot depend on commercial manufacturers alone to design and build the next

  6. Lithium-Ion Batteries Being Evaluated for Low-Earth-Orbit Applications

    NASA Technical Reports Server (NTRS)

    McKissock, Barbara I.

    2005-01-01

    The performance characteristics and long-term cycle life of aerospace lithium-ion (Li-ion) batteries in low-Earth-orbit applications are being investigated. A statistically designed test using Li-ion cells from various manufacturers began in September 2004 to study the effects of temperature, end-of-charge voltage, and depth-of-discharge operating conditions on the cycle life and performance of these cells. Performance degradation with cycling is being evaluated, and performance characteristics and failure modes are being modeled statistically. As technology improvements are incorporated into aerospace Li-ion cells, these new designs can be added to the test to evaluate the effect of the design changes on performance and life. Cells from Lithion and Saft have achieved over 2000 cycles under 10 different test condition combinations and are being evaluated. Cells from Mine Safety Appliances (MSA) and modules made up of commercial-off-the-shelf 18650 Li-ion cells connected in series/parallel combinations are scheduled to be added in the summer of 2005. The test conditions include temperatures of 10, 20, and 30 C, end-of-charge voltages of 3.85, 3.95, and 4.05 V, and depth-of-discharges from 20 to 40 percent. The low-Earth-orbit regime consists of a 55 min charge, at a constant-current rate that is 110 percent of the current required to fully recharge the cells in 55 min until the charge voltage limit is reached, and then at a constant voltage for the remaining charge time. Cells are discharged for 35 min at the current required for their particular depth-of-discharge condition. Cells are being evaluated in four-cell series strings with charge voltage limits being applied to individual cells by the use of charge-control units designed and produced at the NASA Glenn Research Center. These charge-control units clamp the individual cell voltages as each cell reaches its end-of-charge voltage limit, and they bypass the excess current from that cell, while allowing the full

  7. Role of Cu-Ion Doping in Cu-α-MnO 2 Nanowire Electrocatalysts for the Oxygen Reduction Reaction

    DOE PAGES

    Davis, Danae J.; Lambert, Timothy N.; Vigil, Julian A.; ...

    2014-07-09

    The role of Cu-ion doping in α-MnO 2 electrocatalysts for the oxygen reduction reaction in alkaline electrolyte was investigated. Copper doped α-MnO 2 nanowires (Cu-α-MnO 2) were prepared with varying amounts of Cu 2+ using a solvothermal method. The electrocatalytic dataindicates that Cu-α-MnO 2 nanowires have higher terminal current densities, enhanced kinetic rate constants, and improved charge transfer resistances that trend with Cu-content, exceeding values attained by α-MnO 2 alone. The observed improvement in catalytic behavior correlates with an increase in Mn 3+ content for the Cu-α-MnO 2 nanowires. The Mn 3+/Mn 4+ couple is themediator for the rate-limiting redoxmore » driven O 2 -/OH - exchange. It is proposed that O 2 adsorbs viaan axial site (the e g orbital on the Mn 3+ d 4 ion) at the surface, or at edge defects, of the nanowireand that the increase in covalent nature of the nanowire with Cu-ion doping leads to stabilization of O 2 adsorbates and faster rates of reduction. This work is applicable to other manganese oxide electrocatalysts and shows for the first time there is a correlation for manganese oxides between electrocatalytic activity for the ORR in alkaline electrolyte and an increase in Mn 3+ character of the oxide.« less

  8. Enhanced electrochemical properties of F-doped Li2MnSiO4/C for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Xu, Youlong; Sun, Xiaofei; Zhang, Baofeng; Chen, Yanjun; He, Shengnan

    2018-02-01

    The Li2MnSiO4 as a novel cathode material for lithium ion batteries, performs high specific capacity, high thermal stability, low cost and etc. However, it suffers from relatively low electronic conductivity and lithium ion diffusion rate. Herein, we successfully introduce fluorine to Li2MnSiO4 (Li2MnSiO4-xFx, x = 0.00, 0.01, 0.03 and 0.05) to overcome these obstacles. The results show that F doping not only enlarges the lattice parameters but also decreases the particle size, synergistically improving the lithium ion diffusion of Li2MnSiO4. Moreover, F doping increase electronic conductivity of Li2MnSiO4/C by inhibiting the formation of C-O bonds in the carbon layers. Meanwhile, F doping improves the crystallinity and stabilizes the crystal structure of Li2MnSiO4. Finally, the Li2MnSiO3.97F0.03/C with the best electrochemical performances delivers the initial specific discharge capacity of 279 mA h g-1 at 25mA g-1 current density from 1.5 V to 4.8 V. Also, it maintains a higher capacity (201 mA h g-1) than F-free Li2MnSiO4 (145 mA h g-1) after 50 cycles.

  9. Ion-beam-induced ferromagnetism in Ca-doped LaMnO3 thin films grown on Si (100)

    NASA Astrophysics Data System (ADS)

    Sultan, Khalid; Aarif ul Islam, Shah; Habib, Zubida; Ikram, M.; Asokan, K.

    2018-04-01

    The ion-bean-induced room temperature ferromagnetic ordering in pulsed laser deposited Ca-doped LaMnO3 thin films grown on Si (100) are presented in the present study. In addition to this, changes bought by the ion beam in structural, morphological and electrical properties are presented. Dense electronic excitation produced by high energy 120 MeV Ag9+ ion irradiation causes change in surface roughness, crystallinity and strain. It is also evident that these excitations induce the magnetic ordering in this system. The observed modifications are due to the large electronic energy deposited by swift heavy ion irradiation. The appearance of ferromagnetism at 300 K in these samples after irradiation may be attributed to the canting of the antiferromagnetically ordered spins due to the structural distortion. It is observed that the irradiated films show higher resistance than unirradiated films for all the compositions.

  10. An optical investigation of nano-crystalline CaF2 particles doped with Nd3+ ions

    NASA Astrophysics Data System (ADS)

    O'Dwyer, C.; James, H. J.; Cheu, B.; Jaque, F.; Han, T. P. J.

    2017-10-01

    Good crystalline quality CaF2 sub-micron size particles doped with neodymium ions have been produced by the co-precipitation process and their crystallinity have been further improved by thermal treatment at 500 °C. Core and surface related luminescence defect centres have been identified and the effects of Y3+ and Yb3+ codopants are also investigated. Core defects centres are associated with single-ion and multi-ion defect centres as observed in bulk single crystal whereas the origin of the surface or near surface defect, A‧, centre has been ascertained to be derived from a single-ion centre most probably charge compensated by a hydroxyl group.

  11. Nitrogen doped carbon nanodots as fluorescent probes for selective detection and quantification of Ferric(III) ions

    NASA Astrophysics Data System (ADS)

    Chin, Suk-Fun; Tan, Shao-Chien; Pang, Suh-Cem; Ng, Sing-Muk

    2017-11-01

    Nitrogen (N) doped carbon dots (N-CDs) that showed blue fluorescence with quantum yield (QY) of 12.25% were synthesized by one step microwave irradiation of lysine in ortho-phosphoric acid at 1000 W for 5 min. The as-synthesized N-CDs were successfully explored as fluorescent probes for selective detection of ferric (Fe3+) ions in aqueous condition with a linear range from 0.2 to 5.0 mM and a detection limit of 0.074 mM ± 0.081 (S/N = 3). The N-CDs exhibited high selectivity towards the detection of Fe3+ ions even in the presence of interfering ions. The N-CDs also demonstrated the potential of practical application for determining of Fe3+ ions concentration in real samples with high recovery rate and low relative standard deviation error.

  12. Synthesis of praseodymium-ion-doped perovskite nanophosphor in supercritical water

    NASA Astrophysics Data System (ADS)

    Hakuta, Yukiya; Sue, Kiwamu; Takashima, Hiroshi

    2018-05-01

    We report the synthesis of praseodymium-doped calcium strontium titanate nanoparticles, (Ca0.6Sr0.4)0.997Pr0.002TiO3 (PCSTO), using hydrothermal synthesis under supercritical water conditions and the production of red luminescence. Starting solutions were prepared by dissolving calcium nitrate, strontium nitrate, titanium hydroxide sols, and praseodymium nitrate in distilled water. We investigated the effect of the reaction temperature, concentration, and pH of the starting solution on the luminescence properties. Synthesis was conducted at temperatures of 200 °C–400 °C, a reaction pressure of 30 MPa, and for reaction times of 4–20 s. The Pr concentration was set to 0.2 mol% relative to the (Ca0.6Sr0.4) ions. We also investigated the effect of high temperature annealing on the luminescence properties of the PCSTO nanoparticles. Particle characteristics were evaluated using x-ray diffraction, a scanning transmission electron microscope (STEM) equipped with an energy-dispersive x-ray spectrometer, and a fluorometer. Single-phase perovskite particles were obtained at hydrothermal reaction temperatures of over 300 °C even for a reaction time of several seconds. STEM images showed that the particles had cubic-like shapes with diameters of 8–13 nm and that they were chemically homogeneous. The PCSTO nanoparticles exhibited sharp red luminescence at 612 nm corresponding to the f–f transition of Pr3+ ions. Moreover, annealing at 1000 °C led to particle growth, achieving diameters of 40 nm and an increase in the quantum efficiency to around 12.0%.

  13. Stochastic Growth of Ion Cyclotron And Mirror Waves In Earth's Magnetosheath

    NASA Technical Reports Server (NTRS)

    Cairns, Iver H.; Grubits, K. A.

    2001-01-01

    Electromagnetic ion cyclotron and mirror waves in Earth's magnetosheath are bursty, have widely variable fields, and are unexpectedly persistent, properties difficult to reconcile with uniform secular growth. Here it is shown for specific periods that stochastic growth theory (SGT) quantitatively accounts for the functional form of the wave statistics and qualitatively explains the wave properties. The wave statistics are inconsistent with uniform secular growth or self-organized criticality, but nonlinear processes sometimes play a role at high fields. The results show SGT's relevance near marginal stability and suggest that it is widely relevant to space and astrophysical plasmas.

  14. Theoretical Crystal-Field Calculations for Rare-Earth Ions in III-V semiconductor Compounds

    DTIC Science & Technology

    1991-10-01

    AD-A243 098 TIC HDL-TM-91-16 1 Ii! 1 I!EiIII ’ii F CT F October 1991 aC7 1991J Theoretical Crystal-Field Calculations for Rare-Earth Ions in III-V...0188). Washngton. DC 20503 1 . AGENCY USE ONLY (Leave bia*) 2. REPORT DATE 3. REPORT TYPE AND DATES COVERED October 1991 Summary, from Jan 91 toJul 91...Laboratories HDL-TM-9 1 -16 2800 Powder Mill Road Adelphi, MD 20783-1197 9. SPONSORNG#AONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSORINGMONITORING

  15. Effects of rare-earth doping on femtosecond laser waveguide writing in zinc polyphosphate glass

    SciT

    Fletcher, Luke B.; Witcher, Jon J.; Troy, Neil

    We have investigated waveguide writing in Er-Yb doped zinc polyphosphate glass using a femtosecond laser with a repetition rate of 1 KHz. We find that fabrication of good waveguides requires a glass composition with an O/P ratio of 3.25. The dependence on laser writing parameters including laser fluence, focusing conditions, and scan speed is reported. Waveguide properties together with absorption and emission data indicate that these glasses can be used for the fabrication of compact, high gain amplifying devices.

  16. Advancing radiation balanced lasers (RBLs) in rare-earth (RE)-doped solids

    SciT

    Hehlen, Markus Peter

    2016-11-21

    These slides cover the following topics: Mid-IR lasers in crystals using two-tone RBL (Single-dopant two-tone RBLs: Tm 3+, Er 3+, and Co-doped two-tone RBLs: (Yb 3+, Nd 3+) and (Ho 3+, Tm 3+); Advanced approaches to RBL crystals (Precursor purification, Micro-pulling-down crystal growth, and Bridgman crystal growth); Advanced approaches to RBL fibers (Materials for RBL glass fibers, Micro-structured fibers for RBL, and Fiber preform synthesis); and finally objectives.

  17. A comparative study of the magnetization in transition metal ion doped CeO2, TiO2 and SnO2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Apostolov, A. T.; Apostolova, I. N.; Wesselinowa, J. M.

    2018-05-01

    Using the microscopic s-d model taking into account anharmonic spin-phonon interactions we have studied the magnetic properties of Co and Cu ion doped CeO2 and TiO2 nanoparticles and compared them with those of SnO2. By Co-doping there is a maximum in the magnetization M(x) curve for all nanoparticles observed in the most transition metal doped ones. The s-d interaction plays an important role by the decrease of M at higher dopant concentration. We have discussed the magnetization in dependence of different model parameters. By small Cu-ion doping there are some differences. In CeO2M decreases with the Cu-concentration, whereas in TiO2 and SnO2M increases. For higher Cu dopant concentrations M(X) decreases in TiO2 nanoparticles. We obtain room temperature ferromagnetism also in Zn doped CeO2, TiO2 and SnO2 nanoparticles, i.e. in non-transition metal ion doped ones. The different behavior of M in Co and Cu doped nanoparticles is due to a combination effect of multivalent metal ions, oxygen vacancies, different radius of cation dopants, connection between lattice and magnetism, as well as competition between the s-d and d-d ferromagnetic or antiferromagnetic interactions.

  18. Investigations on optical properties of Eu3+ ion doped magnesium telluroborate glasses for red laser applications

    NASA Astrophysics Data System (ADS)

    Arunkumar, S.; Annapoorani, K.; Marimuthu, K.

    2018-04-01

    Eu3+ doped Magnesium telluroborate glasses were prepared with the chemical composition (40-x)H3BO3+35 TeO2+15MgCO3+10MgF2+xEu2O3 (where x = 0.1, 0.5, 1.0 and 2.0 in wt%) following the melt quenching technique and labeled as MTB0.1Eu, MTB0.5Eu, MTB1.0Eu and MTB2.0Eu respectively. The absorption spectra exhibit seven peaks in the visible and NIR region. Five emission peaks corresponding to the 5D0→7FJ (J=0, 1, 2, 3, 4) transitions were observed while exciting at 465 nm. The luminescence intensity ratio (R) and Ω2 parameter values were found to be higher for the MTB0.5Eu glass thus indicates the higher asymmetry around the Eu3+ ions site compared to other prepared glasses. The CIE color chromaticity coordinates of the present glasses are found to lie in the prominent red region in the chromaticity diagram. The stimulated emission cross-section value of the MTB0.5Eu glass was found to be higher pertaining to the 5D0 → 7F2 transition compared to the other prepared glasses and reported literature thus suggests its suitability for red laser applications.

  19. Structural and optical studies on Sm3+ ions doped bismuth fluoroborate glasses for visible laser applications

    NASA Astrophysics Data System (ADS)

    Mariyappan, M.; Suthanthirakumar, P.; Arunkumar, S.; Marimuthu, K.

    2018-04-01

    A new series of Sm3+ doped bismuth fluoroborate glasses have been prepared following the melt quenching technique with the chemical composition (55-x)B2O3+15BiF3+15CaF2+15NaF+xSm2O3 (where x = 0.1, 0.25, 0.5, 1 and 2 in wt%). The structural analysis was made by recording XRD, SEM and EDAX spectra. The XRD pattern reveals the amorphous nature and EDAX confirms the presence of elements in the titled glasses. The optical properties have been explored through recording NIR absorption, photoluminescence spectra. Radiative properties such as transition probability (A), stimulated emission cross-section (σp) and branching ratio (βR) for the 4G5/2 → 6H5/2, 6H7/2, 6H9/2 emission levels were determined. The luminescence quenching for the prominent 4G5/2→6H7/2 emission transition have been observed while increasing the Sm3+ ions concentration beyond 0.5wt%. The CIE chromaticity coordinates of the present glasses lay in the orange-red region thus indicates its suitability for the reddish-orange emission.

  20. Structural and optical properties of lithium sodium borate glasses doped with Sm3+ ions

    NASA Astrophysics Data System (ADS)

    Dawaud, R. S. E. S.; Hashim, S.; Alajerami, Y. S. M.; Mhareb, M. H. A.; Maqableh, M. M.; Tamchek, N.

    2014-07-01

    Absorption and emission spectra of Sm3+ doped lithium sodium borate (LNB) have been reported. The samples were prepared by the melt-quenching technique and characterized by X-ray diffraction (XRD), diffraction thermal analysis (DTA), Fourier transforms infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FESEM). From the thermo-grams spectrum, glass transition (Tg), crystallization (Tc) and melting temperatures (Tm) have been evaluated. Direct and indirect optical band gaps have been calculated based on the glasses UV absorption spectra. These glasses have shown strong nine absorption bands with hypersensitive transition at 1221 nm (6H5/2→4H3/2) and five emission bands for the transition at 4I7/2→6H13/2 (green color), 4I7/2→6H7/2 (orange color), 4I7/2→6H9/2 (orange color), 4I7/2→6H11/2 (red color) and 4I7/2→6H13/2 (red color) with performing an excitation of 400 nm. The oscillator strengths, refractive index, ions concentration, polaron radius and other parameters have been calculated for each dopant.

  1. Optical characterization of Eu3+ and Tb3+ ions doped zinc lead borate glasses.

    PubMed

    Thulasiramudu, A; Buddhudu, S

    2007-02-01

    This paper reports on the spectral analysis of Eu3+ or Tb3+ ions (0.5 mol%) doped heavy metal oxide (HMO) based zinc lead borate glasses from the measurement of their absorption, emission spectra and also different physical properties. From the XRD, DSC profiles, the glass nature and glass thermal properties have been studied. The measured emission spectrum of Eu3+ glass has revealed five transitions (5D0-->7F0, 7F1, 7F2, 7F3 and 7F4) at 578, 591, 613, 654 and 702 nm, respectively, with lambdaexci=392 nm (7F0-->5L6). In the case of Tb3+:ZLB glass, four emission transitions such as (5D4-->7F6, 7F5, 7F4 and 7F3) that are located at 489, 542, 585 and 622 nm, respectively, have been measured with lambdaexci=374 nm. For all these emission bands decay curves have been plotted to evaluate their lifetimes and the emission processes that arise in the glasses have been explained in terms of energy level schemes.

  2. Source of seed fluctuations for electromagnetic ion cyclotron waves in Earth's magnetosphere

    NASA Astrophysics Data System (ADS)

    Gamayunov, K. V.; Engebretson, M. J.; Zhang, M.; Rassoul, H. K.

    2015-06-01

    We consider a nonlinear wave energy cascade from the low frequency range into the higher frequency domain of electromagnetic ion cyclotron (EMIC) wave generation as a possible source of seed fluctuations for EMIC wave growth due to the ion cyclotron instability in Earth's magnetosphere. The presented theoretical analysis shows that energy cascade from the Pc 4-5 frequency range (2-22 mHz) into the range of Pc 1-2 pulsations (0.1-5 Hz), i.e. into the frequency range of EMIC waves, is able to supply the needed level of seed fluctuations that guarantees growth of EMIC waves up to the observable level during one pass through the near equatorial region where the ion cyclotron instability takes place. We also analyze the magnetic field data from the Polar and Van Allen Probes spacecraft to test the suggested nonlinear mechanism. In this initial study we restrict our analysis to magnetic fluctuation spectra only. We do not analyze the third-order structure function, but judge whether a nonlinear energy cascade is present or whether it is not by only analyzing the appearance of power-law distributions in the low-frequency part of the magnetic field spectra. While the power-law spectrum alone does not guarantee that a nonlinear cascade is present, the power-law distribution is a strong indication of the possible development of a nonlinear cascade. Our analysis shows that a nonlinear energy cascade is indeed observed in both the outer and inner magnetosphere data, and EMIC waves are growing from this nonthermal background. All the analyzed data are in good agreement with the theoretical model presented in this study. Overall, the results of this study support a nonlinear energy cascade in Earth's magnetosphere as a mechanism which is responsible for supplying seed fluctuating energy in the higher frequency domain where EMIC waves grow due to the ion cyclotron instability.

  3. Rare earth-doped materials with enhanced thermoelectric figure of merit

    SciT

    Venkatasubramanian, Rama; Cook, Bruce Allen; Levin, Evgenii M.

    A thermoelectric material and a thermoelectric converter using this material. The thermoelectric material has a first component including a semiconductor material and a second component including a rare earth material included in the first component to thereby increase a figure of merit of a composite of the semiconductor material and the rare earth material relative to a figure of merit of the semiconductor material. The thermoelectric converter has a p-type thermoelectric material and a n-type thermoelectric material. At least one of the p-type thermoelectric material and the n-type thermoelectric material includes a rare earth material in at least one ofmore » the p-type thermoelectric material or the n-type thermoelectric material.« less

  4. Spectroscopic and neutron detection properties of rare earth and titanium doped LiAlO 2 single crystals

    DOE PAGES

    Dickens, Peter T.; Marcial, Jose; McCloy, John; ...

    2017-05-17

    In this study, LiAlO 2 crystals doped with rare-earth elements and Ti were produced by the CZ method and spectroscopic and neutron detection properties were investigated. Photoluminescence revealed no clear luminescent activation of LiAlO 2 by the rare-earth dopants though some interesting luminescence was observed from secondary phases within the crystal. Gamma-ray pulse height spectra collected using a 137Cs source exhibited only a Compton edge for the crystals. Neutron modeling using Monte Carlo N-Particle Transport Code revealed most neutrons used in the detection setup are thermalized, and while using natural lithium in the crystal growth, which contains 7.6% 6Li, amore » 10 mm Ø by 10 mm sample of LiAlO 2 has a 70.7% intrinsic thermal neutron capture efficiency. Furthermore, the pulse height spectra collected using a 241Am-Be neutron source demonstrated a distinct neutron peak.« less

  5. Spectroscopic and neutron detection properties of rare earth and titanium doped LiAlO 2 single crystals

    SciT

    Dickens, Peter T.; Marcial, José; McCloy, John

    In this study, LiAlO2 crystals doped with rare-earth elements and Ti were produced by the CZ method and spectroscopic and neutron detection properties were investigated. Photoluminescence revealed no clear luminescent activation of LiAlO2 by the rare-earth dopants though some interesting luminescence was observed from secondary phases within the crystal. Gamma-ray pulse height spectra collected using a 137Cs source exhibited only a Compton edge for the crystals. Neutron modeling using Monte Carlo N-Particle Transport Code revealed most neutrons used in the detection setup are thermalized, and while using natural lithium in the crystal growth, which contains 7.6 % 6Li, a 10more » mm Ø by 10 mm sample of LiAlO2 has a 70.7 % intrinsic thermal neutron capture efficiency. Furthermore, the pulse height spectra collected using a 241Am-Be neutron source demonstrated a distinct neutron peak.« less

  6. Growth and Properties of Oxygen and Ion Doped BISMUTH(2) STRONTIUM(2) Calcium COPPER(2) Oxygen (8+DELTA) Single Crystals

    NASA Astrophysics Data System (ADS)

    Mitzi, David Brian

    1990-01-01

    A directional solidification method for growing large single crystals in the Bi_2Sr _2CaCu_2O _{8+delta} system is reported. Ion substitutions, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Ion doping results in little change of the superconducting transition for substitution levels below 20-25% (as a result of simultaneous oxygen intercalation), while beyond this level, the Meissner signal broadens and the low temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals, provides evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90K (as made) to 77K (oxygen pressure annealed) while the Hall concentrations increase from n = 3.1(3) times 10 ^{21} cm^{ -3} (0.34 holes/Cu site) to 4.6(3) times 10^{21} cm^{-3} (0.50 holes/Cu site). Further suppression of T_{c} to 72K is possible by annealing in oxygen pressures up to 100atm. No degradation of the Meissner transition or other indications of inhomogeneity or phase segregation with doping are noted, suggesting that oxygen doped Bi_2Sr _2CaCu_2O _{8+delta} is a suitable system for pursuing doping studies. The decrease in T _{c} with concentration for 0.34 <=q n <=q 0.50 indicates that a high carrier concentration regime exists where T_{c} decreases with n and suggests that this decrease does not arise from material inhomogeneity or other materials problems. The physical properties of these Bi _2Sr_2CaCu _2O_{8+delta} crystals, in this high carrier concentration regime, will be discussed.

  7. Evaluation of structural and optical properties of Ce3+ ions doped (PVA/PVP) composite films for new organic semiconductors

    NASA Astrophysics Data System (ADS)

    Ali, F. M.; Kershi, R. M.; Sayed, M. A.; AbouDeif, Y. M.

    2018-06-01

    Polymer blend films based on Polyvinyl alcohol (PVA)/Poly(vinylpyrrolidone) (PVP) doped with different concentration of cerium ions [(PVA/PVP)-x wt.% Ce3+] (x = 3%, 5%, 10% and 15%) were prepared by the conventional solution casting technique. The characteristics of the prepared polymer composite films were studied using X-ray diffraction (XRD), FT-IR and UV-Vis. spectroscopy. The XRD patterns of the investigated samples revealed a clear reduction on the structural parameters such as crystallinity degree and cluster size D of the doped PVA/PVP blend films compared with the virgin one whereas there is no big difference in the d spacing of the product composite films. Significant changes in FT-IR spectra are observed which reveal an interactions between the cerium ions and PVA/PVP blends. The absorption spectra in the ultraviolet-visible region showed a wide red shift in the fundamental absorption edge of (PVA/PVP)-x wt. % Ce3+ composites. The optical gap Eg gradually decreased from 4.54 eV for the undoped PVA/PVP film to 3.10 eV by increasing Ce3+ ions content. The optical dispersion parameters have been analyzed according to Wemple-Didomenico single oscillator model. The dispersion energy Ed, the single oscillator energy Eo, the average inter-band oscillator wavelength λo and the static refractive index no are strongly affected by cerium ions doping. Cerium ions incorporation in PVA/PVP blend films leads to a significant increase in the refractive index and decrease in the optical gap. These results are likely of great important in varieties of applications including polymer waveguides, organic semiconductors, polymer solar cells and optoelectronics devices.

  8. Rare-earth doped transparent ceramics for spectral filtering and quantum information processing

    SciT

    Kunkel, Nathalie, E-mail: nathalie.kunkel@chimie-paristech.fr; Goldner, Philippe, E-mail: philippe.goldner@chimie-paristech.fr; Ferrier, Alban

    2015-09-01

    Homogeneous linewidths below 10 kHz are reported for the first time in high-quality Eu{sup 3+} doped Y {sub 2}O{sub 3} transparent ceramics. This result is obtained on the {sup 7}F{sub 0}→{sup 5}D{sub 0} transition in Eu{sup 3+} doped Y {sub 2}O{sub 3} ceramics and corresponds to an improvement of nearly one order of magnitude compared to previously reported values in transparent ceramics. Furthermore, we observed spectral hole lifetimes of ∼15 min that are long enough to enable efficient optical pumping of the nuclear hyperfine levels. Additionally, different Eu{sup 3+} concentrations (up to 1.0%) were studied, resulting in an increase ofmore » up to a factor of three in the peak absorption coefficient. These results suggest that transparent ceramics can be useful in applications where narrow and deep spectral holes can be burned into highly absorbing lines, such as quantum information processing and spectral filtering.« less

  9. Color-coded multilayer photopatterned microstructures using lanthanide (III) ion co-doped NaYF4 nanoparticles with upconversion luminescence for possible applications in security.

    PubMed

    Kim, Won Jin; Nyk, Marcin; Prasad, Paras N

    2009-05-06

    We report a method for fabricating predefined photopatterns of upconversion nanophosphors using a chemical amplification reaction for direct writing of films with multilayer color-coded patterning for security applications. To photopattern the nanocrystal film we have synthesized rare-earth ion (Er(3+)/Yb(3+) or Tm(3+)/Yb(3+)) co-doped sodium yttrium fluoride (alpha-NaYF(4)) nanophosphors and functionalized the nanocrystal surfaces by incorporation of a photopatternable ligand such as t-butoxycarbonyl (t-BOC). The surface modification allows photopatterning of the nanophosphor solid state film. Furthermore, upconversion nanophosphors show a nearly quadratic dependence of the upconversion photoluminescence (PL) intensity on the excitation light power, and tailoring of the PL wavelength is possible by changing the lanthanide ions. We have demonstrated the capability of anchoring nanophosphors at desirable locations by a photolithography technique. The photopatterned films exhibit fixed nanophosphor structures clearly identifiable by strong upconversion photoluminescence under IR illumination which is useful for a number of applications in security.

  10. On the photo-luminescence properties of sol–gel derived undoped and Dy{sup 3+} ion doped nanocrystalline Scheelite type AMoO{sub 4} (A = Ca, Sr and Ba)

    SciT

    Jena, Paramananda; Gupta, Santosh K., E-mail: santufrnd@gmail.com; Natarajan, V.

    2015-04-15

    Nanocrystalline Scheelite type Dy doped AMoO{sub 4} [where A = Ba, Sr and Ca] samples were prepared by acrylamide assisted sol–gel process and characterized by XRD, FT-Raman, FTIR, SEM and photoluminescence (PL). PL of undoped sample shows blue/green emission in CaMoO{sub 4} and SrMoO{sub 4} but multicolour visible emission leading to near white light in BaMoO{sub 4} nanoparticles; the origin of which is explained. It was observed that on doping 0.5 mol% of Dy{sup 3+} in molybdate samples complete energy transfer takes place in case of SrMoO{sub 4} and BaMoO{sub 4}, but host contributed substantially in Dy doped BaMoO{sub 4}more » sample, resulting in biexponential decay. It was also observed that symmetry around Dy{sup 3+} decreases as the size of alkaline earth ion increases. Due to combined blue, yellow and red colour emission in dysprosium doped sample; all samples showed near white light emission under UV and near UV excitation.« less

  11. Silver ion doped ceramic nano-powder coated nails prevent infection in open fractures: In vivo study.

    PubMed

    Kose, Nusret; Çaylak, Remzi; Pekşen, Ceren; Kiremitçi, Abdurrahman; Burukoglu, Dilek; Koparal, Savaş; Doğan, Aydın

    2016-02-01

    Despite improvement in operative techniques and antibiotic therapy, septic complications still occur in open fractures. We developed silver ion containing ceramic nano powder for implant coating to provide not only biocompatibility but also antibacterial activity to the orthopaedic implants. We hypothesised silver ion doped calcium phosphate based ceramic nano-powder coated titanium nails may prevents bacterial colonisation and infection in open fractures as compared with uncoated nails. 33 rabbits divided into three groups. In the first group uncoated, in the second group hydroxyapatite coated, and in the third group silver doped hydroxyapatite coated titanium nails were inserted left femurs of animals from knee regions with retrograde fashion. Before implantation of nails 50 μl solution containing 10(6)CFU/ml methicillin resistance Staphylococcus aureus (MRSA) injected intramedullary canal. Rabbits were monitored for 10 weeks. Blood was taken from rabbits before surgery and on 2nd, 6th and 10th weeks. Blood was analysed for biochemical parameters, blood count, C-reactive protein and silver levels. At the end of the 10 weeks animals were sacrificed and rods were extracted in a sterile fashion. Swab cultures were taken from intramedullary canal. Bacteria on titanium rods were counted. Liver, heart, spleen, kidney and central nervous tissues samples were taken for determining silver levels. Histopathological evaluation of bone surrounding implants was also performed. No significant difference was detected between the groups from hematologic, biochemical, and toxicological aspect. Microbiological results showed that less bacterial growth was detected with the use of silver doped ceramic coated implants compared to the other two groups (p=0.003). Accumulation of silver was not detected. No cellular inflammation was observed around the silver coated prostheses. No toxic effect of silver on bone cells was seen. Silver ion doped calcium phosphate based ceramic nano

  12. Bond-length distributions for ions bonded to oxygen: alkali and alkaline-earth metals.

    PubMed

    Gagné, Olivier Charles; Hawthorne, Frank Christopher

    2016-08-01

    Bond-length distributions have been examined for 55 configurations of alkali-metal ions and 29 configurations of alkaline-earth-metal ions bonded to oxygen, for 4859 coordination polyhedra and 38 594 bond distances (alkali metals), and for 3038 coordination polyhedra and 24 487 bond distances (alkaline-earth metals). Bond lengths generally show a positively skewed Gaussian distribution that originates from the variation in Born repulsion and Coulomb attraction as a function of interatomic distance. The skewness and kurtosis of these distributions generally decrease with increasing coordination number of the central cation, a result of decreasing Born repulsion with increasing coordination number. We confirm the following minimum coordination numbers: ([3])Li(+), ([3])Na(+), ([4])K(+), ([4])Rb(+), ([6])Cs(+), ([3])Be(2+), ([4])Mg(2+), ([6])Ca(2+), ([6])Sr(2+) and ([6])Ba(2+), but note that some reported examples are the result of extensive dynamic and/or positional short-range disorder and are not ordered arrangements. Some distributions of bond lengths are distinctly multi-modal. This is commonly due to the occurrence of large numbers of structure refinements of a particular structure type in which a particular cation is always present, leading to an over-representation of a specific range of bond lengths. Outliers in the distributions of mean bond lengths are often associated with anomalous values of atomic displacement of the constituent cations and/or anions. For a sample of ([6])Na(+), the ratio Ueq(Na)/Ueq(bonded anions) is partially correlated with 〈([6])Na(+)-O(2-)〉 (R(2) = 0.57), suggesting that the mean bond length is correlated with vibrational/displacement characteristics of the constituent ions for a fixed coordination number. Mean bond lengths also show a weak correlation with bond-length distortion from the mean value in general, although some coordination numbers show the widest variation in mean bond length for zero distortion, e.g. Li(+) in

  13. Energy transfer and up-conversion in rare-earth doped dielectric crystals

    NASA Astrophysics Data System (ADS)

    Tkachuk, Alexandra M.

    1996-01-01

    In this work, we consider the prospects of development of the visible, and IR laser-diode pumped lasers based on TR3+-doped double-fluoride crystals. On the basis of estimates of the probabilities of competing non-radiative energy-transfer processes obtained from the experiments and theoretical calculations, the conclusions are drawn on the efficiency of up-conversion pumping and selfquenching of the upper TR3+ states excited by laser-diode emission. The effect of the host composition, dopant concentration, and temperature on the efficiency of up-conversion processes is demonstrated on the example of the YLF:Nd, YLF:Er, BaY2F8:Er, and BaY2F8:Er,Yb crystals. The transfer microparameters for most important cross-relaxation transitions are determined and the conclusions about interaction mechanisms are drawn.

  14. Discovery of ions with nuclear charge Z greater than or equal to 9 stability trapped in the earth's radiation belts

    NASA Astrophysics Data System (ADS)

    Spjeldvik, W. N.; Fritz, T. A.

    1981-11-01

    Observations of MeV heavy ions obtained by Explorer 45 in an equatorial earth orbit during a 7 month period in 1972 are presented, including data from four major magnetic storms. The spacecraft contained a heavy ion detector telescope and heavy ion discriminator electronics. Heavy ions were distinguished from protons and electrons, and He ions and ions heavier than F were recorded on separate data channels. The L equals 2.25 to L equals 4 zones were probed, and it was found that the relative enhancement in heavy ion fluxes in the radiation belts over the prestorm ion flux intensities tends to increase with increasing ion mass and/or increasing ion energy in the MeV range. The radial profiles of ions with nucleon number greater than nine peak at L equals 2.9, and MeV ions in this class decay on time scales from 23 days at L equals 3.25 to 55 days at L equals 2.25. Indirect evidence indicated a solar source for the very heavy ions in the magnetosphere.

  15. Ion Acceleration at Earth, Saturn and Jupiter and its Global Impact on Magnetospheric Structure

    NASA Astrophysics Data System (ADS)

    Brandt, Pontus

    2016-07-01

    The ion plasma pressures at Earth, Saturn and Jupiter are significant players in the electrodynamic force-balance that governs the structure and dynamics of these magnetospheres. There are many similarities between the physical mechanisms that are thought to heat the ion plasma to temperatures that even exceed those of the solar corona. In this presentation we compare the ion acceleration mechanisms at the three planetary magnetospheres and discuss their global impacts on magnetopsheric structure. At Earth, bursty-bulk flows, or "bubbles", have been shown to accelerate protons and O+ to high energies by the earthward moving magnetic dipolarization fronts. O+ ions display a more non-adiabatic energization in response to these fronts than protons do as they are energized and transported in to the ring-current region where they reach energies of several 100's keV. We present both in-situ measurements from the NASA Van Allen Probes Mission and global Energetic Neutral (ENA) images from the High-Energy Neutral Atom (HENA) Camera on board the IMAGE Mission, that illustrate these processes. The global impact on the magnetospheric structure is explored by comparing the empirical magnetic field model TS07d for given driving conditions with global plasma pressure distributions derived from the HENA images. At Saturn, quasi-periodic energization events, or large-scale injections, occur beyond about 9 RS around the post-midnight sector, clearly shown by the Ion and Neutral Atom Camera (INCA) on board the Cassini mission. In contrast to Earth, the corotational drift dominates even the energetic ion distributions. The large-scale injections display similar dipolarization front features can be found and there are indications that like at Earth the O+ responds more non-adiabatically than protons do. However, at Saturn there are also differences in that there appears to be energization events deep in the inner magnetosphere (6-9 RS) preferentially occurring in the pre

  16. Alkali earth co-doping effects on luminescence and scintillation properties of Ce doped Gd3Al2Ga3O12 scintillator

    NASA Astrophysics Data System (ADS)

    Kamada, Kei; Nikl, Martin; Kurosawa, Shunsuke; Beitlerova, Alena; Nagura, Aya; Shoji, Yasuhiro; Pejchal, Jan; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

    2015-03-01

    The Mg and Ca co-doped Ce:Gd3Al2Ga3O12 single crystals were prepared by micro pulling down method with a wide concentration range 0-1000 ppm of the codopants. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of Mg and Ca co-doping. The scintillation decays were accelerated by both Mg and Ca codopants. Comparing to Ca co-doping, the Mg co-doped samples showed much faster decay and comparatively smaller light output decrease with increasing Mg dopant concentration.

  17. Enhancing the luminescence of Eu3+ /Eu2+ ion-doped hydroxyapatite by fluoridation and thermal annealing.

    PubMed

    Van, Hoang Nhu; Tam, Phuong Dinh; Kien, Nguyen Duc Trung; Huy, Pham Thanh; Pham, Vuong-Hung

    2017-08-01

    This paper reports a novel way for the synthesis of a europium (Eu)-doped fluor-hydroxyapatite (FHA) nanostructure to control the luminescence of hydroxyapatite nanophosphor, particularly, by applying optimum fluorine concentrations, annealed temperatures and pH value. The Eu-doped FHA was made using the co-precipitation method followed by thermal annealing in air and reducing in a H 2 atmosphere to control the visible light emission center of the nanophosphors. The intensities of the OH - group decreased with the increasing fluorine concentrations. For the specimens annealed in air, the light emission center of the nanophosphor was 615 nm, which was emission from the Eu 3 + ion. However, when they were annealed in reduced gas (Ar + 5% H 2 ), a 448 nm light emission center from the Eu 2 + ion of FHA was observed. The presence of fluorine in Eu-doped FHA resulted in a significant enhancement of nanophosphor luminescence, which has potential application in light emission and nanomedicine. Copyright © 2016 John Wiley & Sons, Ltd.

  18. Structural, thermal and optical investigations of Dy3+ ions doped lead containing lithium fluoroborate glasses for simulation of white light

    NASA Astrophysics Data System (ADS)

    Zulfiqar Ali Ahamed, Sd.; Madhukar Reddy, C.; Deva Prasad Raju, B.

    2013-05-01

    Lead containing barium zinc lithium fluoroborate (LBZLFB) glasses doped with different concentrations of trivalent dysprosium ions were synthesized by conventional melt quenching method and characterized through the XRD, DSC, FTIR, FT-Raman, optical absorption, photoluminescence and decay curve analysis. X-ray diffraction studies revealed amorphous nature of the studied glass matrices. The thermal behavior has been reported by recording DSC thermograms. Coexistence of trigonal BO3 and tetrahedral BO4 units was evidenced by IR and Raman spectroscopy. Judd-Ofelt intensity parameters have been evaluated for 1.0 mol% Dy3+ ions doped LBZLFB glass. The measuring branching ratios are reasonably high for transitions 4F9/2 → 6H15/2 and 6H13/2 suggesting that the emission at 486 and 577 nm, respectively can give rise to lasing action in the visible region. From the visible emission spectra, the yellow to blue (Y/B) intensity ratios and chromaticity color coordinates were estimated. A combination of blue and yellow emissions has emerged in the glasses, which allows the observation of white light when the glasses are excited by the ultraviolet/blue light. These Dy3+ doped glasses are studied for their utility for white light generation under 454 nm excitation and the present LBZLFB glass is more suitable for generation of white light for blue LED chips.

  19. The stable and water-soluble neodymium-doped lanthanide fluoride nanoparticles for near infrared probing of copper ion.

    PubMed

    Xue, Fang-Min; Wang, He-Fang

    2012-09-15

    Neodymium (Nd(3+)) doped nanomaterials exhibited the unique near infrared (NIR) luminescence properties. However, the application of Nd-doped nanomaterials to chemosensors was rarely explored. Herein, the water-soluble 2-aminoethyl dihydrogen phosphate stabilized Nd-doped LaF(3) (ADP-Nd-LaF(3)) nanoparticles were explored as the NIR probe for chemosensors. The NIR emission intensity at 1061 nm of ADP-Nd-LaF(3) nanoparticles kept stable in the aqueous solution of various pH and coexisting of most common metal ions except copper ion, consequently, the ADP-Nd-LaF(3) nanoparticles were developed as a high selective NIR probe for Cu(II). The NIR emission of ADP-Nd-LaF(3) exhibits a linear quenching response to Cu(II) in the range 5-100 μM, with a detection limit of 0.8 μM. The precision of eleven replicate detections of 5 μM Cu(II) was 0.5% (RSD). The recovery of spiked Cu(II) in human urine and waste water samples ranged from 102 to 109%. The possible mechanism of Cu(II)-induced fluorescence quenching of ADP-Nd-LaF(3) nanoparticles was also discussed. Copyright © 2012 Elsevier B.V. All rights reserved.

  20. Highly crystalline lithium titanium oxide sheets coated with nitrogen-doped carbon enable high-rate lithium-ion batteries.

    PubMed

    Han, Cuiping; He, Yan-Bing; Li, Baohua; Li, Hongfei; Ma, Jun; Du, Hongda; Qin, Xianying; Yang, Quan-Hong; Kang, Feiyu

    2014-09-01

    Sheets of Li4Ti5O12 with high crystallinity are coated with nitrogen-doped carbon (NC-LTO) using a controlled process, comprising hydrothermal reaction followed by chemical vapor deposition (CVD). Acetonitrile (CH3 CN) vapor is used as carbon and nitrogen source to obtain a thin coating layer of nitrogen-doped carbon. The layer enables the NC-LTO material to maintain its sheet structure during the high-temperature CVD process and to achieve high crystallinity. Doping with nitrogen introduces defects into the carbon coating layer, and this increased degree of disorder allows fast transportation of lithium ions in the layer. An electrode of NC-LTO synthesized at 700 °C exhibits greatly improved rate and cycling performance due to a markedly decreased total cell resistance and enhanced Li-ion diffusion coefficient (D(Li)). Specific capacities of 159.2 and 145.8 mA h g(-1) are obtained using the NC-LTO sheets, at charge/discharge rates of 1 and 10 C, respectively. These values are much higher than values for LTO particles did not undergo the acetonitrile CVD treatment. A capacity retention value as high as 94.7% is achieved for the NC-LTO sheets after 400 cycles in a half-cell at 5 C discharge rate. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Rapid synthesis of N, S co-doped carbon dots and their application for Fe3+ ion detection

    NASA Astrophysics Data System (ADS)

    Zhang, Jian; Wang, Junbin; Fu, Jinping; Fu, Xucheng; Gan, Wei; Hao, Hequn

    2018-02-01

    In this study, nitrogen and sulfur co-doped carbon dots (NSCDs) were fabricated by microwave-assisted one-pot synthesis using vitamin C and thiourea as precursors. The as-prepared NSCDs demonstrated excellent properties, including aqueous dispensability, strong fluorescence emission, excellent environmental stability, high selectivity, and sensitivity toward Fe3+ ions. The NSCD-based material can be used as a "turn off" fluorescent probe for detecting Fe3+ ions at a low detection limit (4.2 nM). In addition, the "turn off" and "turn on" of NSCD fluorescent probe could be modulated by adding Fe3+ and EDTA, indicating weak interaction between the Fe3+ ions and NSCDs.

  2. Toward a System-Based Approach to Electromagnetic Ion Cyclotron Waves in Earth's Magnetosphere

    NASA Astrophysics Data System (ADS)

    Gamayunov, K. V.; Engebretson, M. J.; Rassoul, H.

    2015-12-01

    We consider a nonlinear wave energy cascade from the low frequency range into the higher frequency domain of electromagnetic ion cyclotron (EMIC) wave generation as a possible source of seed fluctuations for EMIC wave growth due to the ion cyclotron instability in Earth's magnetosphere. The theoretical analysis shows that energy cascade from the Pc 4-5 frequency range (2-22 mHz) into the range of Pc 1-2 pulsations (0.1-5 Hz) is able to supply the level of seed fluctuations that guarantees growth of EMIC waves up to an observable level during one pass through the near equatorial region where the ion cyclotron instability takes place. We also analyze magnetic field data from the Polar and Van Allen Probes spacecraft to test this nonlinear mechanism. We restrict our analysis to magnetic spectra only. We do not analyze the third-order moment for total energy of the magnetic and velocity fluctuations, but judge whether a nonlinear energy cascade is present or whether it is not by only analyzing the appearance of power-law distributions in the low frequency part of the magnetic field spectra. While the power-law spectrum alone does not guarantee that a nonlinear cascade is present, the power-law distribution is a strong indication of the possible development of a nonlinear cascade. Our data analysis shows that a nonlinear energy cascade is indeed observed in both the outer and inner magnetosphere, and EMIC waves are growing from this nonthermal background. All the analyzed data are in good agreement with the theoretical model presented in this study. Overall, the results of this study support a nonlinear energy cascade in Earth's magnetosphere as a mechanism which is responsible for supplying seed fluctuating energy in the higher frequency domain where EMIC waves grow due to the ion cyclotron instability. Keywords: nonlinear energy cascade, ultra low frequency waves, electromagnetic ion cyclotron waves, seed fluctuationsAcknowledgments: This paper is based upon work

  3. Population gratings in saturable optical fibers with randomly oriented rare-earth ions

    NASA Astrophysics Data System (ADS)

    Stepanov, S.; Martinez, L. M.; Hernandez, E. H.; Agruzov, P.; Shamray, A.

    2015-07-01

    Formation of the dynamic population gratings in optical fibers with randomly oriented rare-earth ions is analyzed with a special interest to the grating component for readout with the orthogonal light polarization. It is shown that as compared with a simple model case of the collinearly oriented dipole-like centers their random orientation leads to approximately 2-times growth of the effective saturation power P sat when it is estimated from the incident power dependence of the fiber absorption or from that of the fluorescence intensity. An optimal incident power, for which the maximum of the dynamic population grating amplitude for collinear light polarization is observed, also follows this change in P sat, while formation of the grating for orthogonal polarization needs essentially higher light power. The reduced anisotropy of the active centers, which is in charge of the experimentally observed weakening of the polarization hole burning (PHB) and of the fluorescence polarization, compensates in some way the effect of random ion orientation. The ratio between the maximum conventional (i.e. for the interacting waves collinear polarizations) two-wave mixing (TWM) amplitude and the initial not saturable fiber optical density proves to be, however, nearly the same as in the model case of collinearly oriented dipoles. The ratio between the PHB effect and the amplitude of the anisotropic grating, which is responsible for TWM of the orthogonally polarized waves, is also not influenced significantly by the reduced anisotropy of ions.

  4. A primary exploration to quasi-two-dimensional rare-earth ferromagnetic particles: holmium-doped MoS2 sheet as room-temperature magnetic semiconductor

    NASA Astrophysics Data System (ADS)

    Chen, Xi; Lin, Zheng-Zhe

    2018-05-01

    Recently, two-dimensional materials and nanoparticles with robust ferromagnetism are even of great interest to explore basic physics in nanoscale spintronics. More importantly, room-temperature magnetic semiconducting materials with high Curie temperature is essential for developing next-generation spintronic and quantum computing devices. Here, we develop a theoretical model on the basis of density functional theory calculations and the Ruderman-Kittel-Kasuya-Yoshida theory to predict the thermal stability of two-dimensional magnetic materials. Compared with other rare-earth (dysprosium (Dy) and erbium (Er)) and 3 d (copper (Cu)) impurities, holmium-doped (Ho-doped) single-layer 1H-MoS2 is proposed as promising semiconductor with robust magnetism. The calculations at the level of hybrid HSE06 functional predict a Curie temperature much higher than room temperature. Ho-doped MoS2 sheet possesses fully spin-polarized valence and conduction bands, which is a prerequisite for flexible spintronic applications.

  5. High-performance tin oxide-nitrogen doped graphene aerogel hybrids as anode materials for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Tan, Chunhui; Cao, Jing; Khattak, Abdul Muqsit; Cai, Feipeng; Jiang, Bo; Yang, Gai; Hu, Suqin

    2014-12-01

    Tin dioxide nanoparticles on nitrogen doped graphene aerogel (SnO2-NGA) hybrid are synthesized by one-step hydrothermal method and successfully applied in lithium-ion batteries as a free-standing anode. The electrochemical performance of SnO2-NGA hybrid is investigated by galvanostatic charge-discharge cycling, rate capability test, cyclic voltammetry and electrochemical impedance spectroscopy. It is found that the SnO2-NGA hybrid with freestanding spongy-like structure exhibit remarkable lithium storage capacity (1100 mAh g-1 after 100 cycles), good cycling stability and high rate capability. The outstanding performance is attributed to the uniform SnO2 nanoparticles, unique spongy-like structure and N doping defect for Li+ diffusion.

  6. Enhanced visible light activity of nano-titanium dioxide doped with multiple ions: Effect of crystal defects

    NASA Astrophysics Data System (ADS)

    Jaimy, Kanakkanmavudi B.; Ghosh, Swapankumar; Gopakumar Warrier, Krishna

    2012-12-01

    Titanium dioxide photocatalysts co-doped with iron(III) and lanthanum(III) have been prepared through a modified sol-gel method. Doping with Fe3+ resulted in a relatively lower anatase to rutile phase transformation temperature, while La3+ addition reduced the crystal growth and thus retarded the phase transformation of titania nanoparticles. The presence of Fe3+ ions shifted the absorption profile of titania to the longer wavelength side of the spectrum and enhanced the visible light activity. On the other hand, La3+ addition improved the optical absorption of titania nanoparticles. Both the dopants improved the life time of excitons by proper transferring and trapping of photoexcited charges. In the present work, considerable enhancement in photocatalytic activity under visible light was achieved through synergistic effect of optimum concentrations of the two dopants and associated crystal defects.

  7. Characterization and Comparison of Photocatalytic Activity Silver Ion doped on TiO2(TiO2/Ag+) and Silver Ion doped on Black TiO2(Black TiO2/Ag+)

    NASA Astrophysics Data System (ADS)

    Kim, Jin Yi; Sim, Ho Hyung; Song, Sinae; Noh, Yeoung Ah; Lee, Hong Woon; Taik Kim, Hee

    2018-03-01

    Titanium dioxide (TiO2) is one of the representative ceramic materials containing photocatalyst, optic and antibacterial activity. The hydroxyl radical in TiO2 applies to the intensive oxidizing agent, hence TiO2 is suitable to use photocatalytic materials. Black TiO2was prepared through reduction of amorphous TiO2 conducting under H2 which leads to color changes. Its black color is proven that absorbs 100% light across the whole-visible light, drawing enhancement of photocatalytic property. In this study, we aimed to compare the photocatalytic activity of silver ion doped on TiO2(TiO2/Ag+) and silver ion doped on black TiO2(black TiO2/Ag+) under visible light range. TiO2/Ag+ was fabricated following steps. 1) TiO2 was synthesized by a sol-gel method from Titanium tetraisopropoxide (TTIP). 2) Then AgNO3 was added during an aging process step for silver ion doping on the surface of TiO2. Moreover, Black TiO2/Ag+ was obtained same as TiO2/Ag+ except for calcination under H2. The samples were characterized X-ray diffraction (XRD), UV-visible reflectance (UV-vis DRS), and Methylene Blue degradation test. XRD analysis confirmed morphology of TiO2. The band gap of black TiO2/Ag+ was confirmed (2.6 eV) through UV-vis DRS, which was lower than TiO2/Ag+ (2.9 eV). The photocatalytic effect was conducted by methylene blue degradation test. It demonstrated that black TiO2/Ag+ had a photocatalytic effect under UV light also visible light.

  8. An Update on the Lithium-Ion Cell Low-Earth-Orbit Verification Test Program

    NASA Technical Reports Server (NTRS)

    Reid, Concha M.; Manzo, Michelle A.; Miller, Thomas B.; McKissock, Barbara I.; Bennett, William

    2007-01-01

    A Lithium-Ion Cell Low-Earth-Orbit Verification Test Program is being conducted by NASA Glenn Research Center to assess the performance of lithium-ion (Li-ion) cells over a wide range of low-Earth-orbit (LEO) conditions. The data generated will be used to build an empirical model for Li-ion batteries. The goal of the modeling will be to develop a tool to predict the performance and cycle life of Li-ion batteries operating at a specified set of mission conditions. Using this tool, mission planners will be able to design operation points of the battery system while factoring in mission requirements and the expected life and performance of the batteries. Test conditions for the program were selected via a statistical design of experiments to span a range of feasible operational conditions for LEO aerospace applications. The variables under evaluation are temperature, depth-of-discharge (DOD), and end-of-charge voltage (EOCV). The baseline matrix was formed by generating combinations from a set of three values for each variable. Temperature values are 10 C, 20 C and 30 C. Depth-of-discharge values are 20%, 30% and 40%. EOCV values are 3.85 V, 3.95 V, and 4.05 V. Test conditions for individual cells may vary slightly from the baseline test matrix depending upon the cell manufacturer s recommended operating conditions. Cells from each vendor are being evaluated at each of ten sets of test conditions. Cells from four cell manufacturers are undergoing life cycle tests. Life cycling on the first sets of cells began in September 2004. These cells consist of Saft 40 ampere-hour (Ah) cells and Lith ion 30 Ah cells. These cells have achieved over 10,000 cycles each, equivalent to about 20 months in LEO. In the past year, the test program has expanded to include the evaluation of Mine Safety Appliances (MSA) 50 Ah cells and ABSL battery modules. The MSA cells will begin life cycling in October 2006. The ABSL battery modules consist of commercial Sony hard carbon 18650 lithium-ion

  9. Nucleation-dependant chemical bonding paradigm: the effect of rare earth ions on the nucleation of urea in aqueous solution.

    PubMed

    Chen, Xiaoyan; Sun, Congting; Wu, Sixin; Xue, Dongfeng

    2017-03-29

    Rare earth ions can be used to construct a variety of novel structures and are favorable to chemical bonding regulation and design. In this study, the chemical bonding paradigm between rare earth ions (Ln 3+ ) and urea molecules in an aqueous solution can be tracked by the evolution of C[double bond, length as m-dash]O, NH 2 , and CN vibration bands during the urea nucleation stage. Rare earth ions such as La 3+ , Gd 3+ , and Lu 3+ can manipulate the nucleation time of urea via regulating the nucleation-dependant N-C[double bond, length as m-dash]OH-N hydrogen-bonding between urea molecules. Two types of chemical bondings between Ln 3+ and urea molecules have been confirmed, which are Ln 3+ O[double bond, length as m-dash]C-N and Ln 3+ NH 2 -C. Compared with Ln 3+ NH 2 -C, Ln 3+ prefers to coordinate with the O[double bond, length as m-dash]C bond in urea. With a higher concentration of rare earth ions in the solution, some N-C[double bond, length as m-dash]OH-N hydrogen bonds are broken as a consequence of the incorporation of Ln 3+ into the lattice, resulting in the decreased symmetry of local urea molecules in the crystalline nuclei and the consequent Ln 3+ concentration-dependent nucleation time of urea. Moreover, using the ionic electronegativity scale of Ln 3+ , the different effects of La 3+ , Gd 3+ , and Lu 3+ on urea nucleation can be further distinguished. The present study provides basic data for unrevealing the chemical bonding regulation role of rare earth ions in the formation of hydrogen bonded materials, which may give insight into the design and fabrication of novel materials utilizing rare earth ions to adjust the chemical bonding process.

  10. Luminescent rare earth vanadate nanoparticles doped with Eu3+ and Bi3 for sensing and imaging applications

    NASA Astrophysics Data System (ADS)

    Escudero, Alberto; Carrillo-Carrión, Carolina; Zyuzin, Mikhail; Hartmann, Raimo; Ashraf, Sumaira; Parak, Wolfgang J.

    2016-03-01

    Nanoparticles (NPs) are attracting interest in nanomedicine due to their potential medical applications, ranging from optical biolabels and contrast agents for magnetic resonance imaging to carriers for drug and gene delivery for disease therapy.[1] Rare earth (RE) based nanophosphors exhibit important advantages compared with other available luminescent materials, such as quantum dots and nanostructures functionalized with organic dyes, due to their lower toxicities, photostabilities, high thermal and chemical stabilities, high luminescence quantum yields, and sharp emission bands.[2] Yttrium orthovanadate NPs doped with Eu3+ and Bi3+, functionalized with poly acryl acid (PAA), and excitable by near-ultraviolet light have been synthesized by homogeneous precipitation at 120 °C from solutions of rare earth precursors (yttrium acetylacetonate and europium nitrate), bismuth nitrate, sodium orthovanadate, and PAA, in an ethylene glycol/water mixture. Quasispheres with sizes from 93 to 51 nm were obtained. The as synthesized NPs were already functionalized with PAA. The NPs showed the typical red luminescence of Eu3+, which can be excited with near-UV light through an energy transfer from the vanadate anion. The presence of Bi3+ shifts the maximum of the broad excitation band from 280 nm to 342 nm. This excitation path is much more efficient than the direct excitation of the Eu3+ electronic levels, and results in a much higher luminescence. The NPs can be uptaken by HeLa cells, and are eventually located in the lysosomes after being internalized. Finally, the functionalization with PAA provides -COOH anchors for adding functional ligands of biomedical interest that can be used for sensing applications.

  11. Effect of Fe-ion implantation doping on structural and optical properties of CdS thin films

    NASA Astrophysics Data System (ADS)

    Chandramohan, S.; Kanjilal, A.; Sarangi, S. N.; Majumder, S.; Sathyamoorthy, R.; Som, T.

    2010-06-01

    We report on effects of Fe implantation doping-induced changes in structural, optical, morphological, and vibrational properties of cadmium sulfide thin films. Films were implanted with 90 keV Fe+ ions at room temperature for a wide range of fluences from 0.1×1016 to 3.6×1016 ions cm-2 (corresponding to 0.38-12.03 at.% of Fe). Glancing angle X-ray diffraction analysis revealed that the implanted Fe atoms tend to supersaturate by occupying the substitutional cationic sites rather than forming metallic clusters or secondary phase precipitates. In addition, Fe doping does not lead to any structural phase transformation although it induces structural disorder and lattice contraction. Optical absorption studies show a reduction in the optical band gap from 2.39 to 2.17 eV with increasing Fe concentration. This is attributed to disorder-induced band tailing in semiconductors and ion-beam-induced grain growth. The strain associated with a lattice contraction is deduced from micro-Raman scattering measurements and is found that size and shape fluctuations of grains, at higher fluences, give rise to inhomogeneity in strain.

  12. First simultaneous detection of terrestrial ionospheric molecular ions in the Earth's inner magnetosphere and at the Moon

    NASA Astrophysics Data System (ADS)

    Dandouras, I.; Poppe, A. R.; Fillingim, M. O.; Kistler, L. M.; Mouikis, C. G.; Rème, H.

    2017-09-01

    First coordinated observation of escaping heavy molecular ions in the Earth's inner magnetosphere and at the Moon. Quantifying the underlying escape mechanisms is important in order to understand the long-term (billion years scale) evolution of the atmospheric composition, and in particular the evolution of the N/O ratio, which is essential for habitability. Terrestrial heavy ions, transported to the Moon, suggest also that the Earth's atmosphere of billions of years ago may be preserved on the present-day lunar regolith.

  13. Towards atomic scale engineering of rare-earth-doped SiAlON ceramics through aberration-corrected scanning transmission electron microscopy

    SciT

    Yurdakul, Hilmi; Idrobo Tapia, Juan C; Pennycook, Stephen J

    2011-01-01

    Direct visualization of rare earths in {alpha}- and {beta}-SiAlON unit-cells is performed through Z-contrast imaging technique in an aberration-corrected scanning transmission electron microscope. The preferential occupation of Yb and Ce atoms in different interstitial locations of {beta}-SiAlON lattice is demonstrated, yielding higher solubility for Yb than Ce. The triangular-like host sites in {alpha}-SiAlON unit cell accommodate more Ce atoms than hexagonal sites in {beta}-SiAlON. We think that our results will be applicable as guidelines for many kinds of rare-earth-doped materials.

  14. A review of visible, near-IR, and mid-IR transitions in rare-earth doped glass waveguides for remote sensing and LIDAR

    NASA Astrophysics Data System (ADS)

    Jha, Animesh

    2006-12-01

    In the review article we explain the recent investigations on rare-earth doped glass and optical fibres for designing lasers which may be suitable for remote sensing and LIDAR applications. The paper explains the importance of engineering efficient lasing transitions in visible (480-650 nm) for generating UV lasers via one-stage harmonic generation. Besides visible transitions, we also demonstrate the transitions in near- and mid-IR via near-IR pumping scheme.

  15. Mid-IR lasers based on transition metal and rare-earth ion doped crystals

    NASA Astrophysics Data System (ADS)

    Mirov, S.; Fedorov, V.; Martyshkin, D.; Moskalev, I.; Mirov, M.; Vasilyev, S.

    2015-05-01

    We report a novel design of CW Cr2+:ZnS/ZnSe laser systems and demonstrate record output powers of 27.5 W at 2.45 μm and 13.9 W at 2.94 μm with slope efficiencies of 63.7% and 37.4%, respectively. Power scaling of ultra-fast Cr2+:ZnS/ZnSe Kerr mode-locked lasers beyond 2 W level, as well as the shortest pulse duration of 29 fs, are also reported. New development of Fe:ZnSe laser with average output power > 35 W at 4.1 μm output wavelength and 100 Hz pulse repetition rate (PRR) was achieved in a nonselective cavity. With intracavity prim selector, wavelength tunability of 3.88-4.17 μm was obtained with maximum average output power of 23 W. We also report new results on Tm-fiber pumped passively and actively Q-switched Ho:YAG laser systems. High peak power actively Q-switched Ho:YAG laser demonstrates stable operation with pulse energy > 50 mJ, 12 ns pulse duration, and 100-1000 Hz PRR which correspondents to more than 4 MW peak power. The actively Q-switched Ho:YAG laser system optimized for high repetition rate delivers 40 W average output power at 10-100 kHz PRR. The Ho:YAG laser with passive Q-switcher demonstrates constant 5 mJ output energy from 200 Hz to 2.23 kHz PRR with optical slope efficiency with respect to Tm-fiber laser of ~43%.

  16. Phase, current, absorbance, and photoluminescence of double and triple metal ion-doped synthetic and salmon DNA thin films

    NASA Astrophysics Data System (ADS)

    Chopade, Prathamesh; Reddy Dugasani, Sreekantha; Reddy Kesama, Mallikarjuna; Yoo, Sanghyun; Gnapareddy, Bramaramba; Lee, Yun Woo; Jeon, Sohee; Jeong, Jun-Ho; Park, Sung Ha

    2017-10-01

    We fabricated synthetic double-crossover (DX) DNA lattices and natural salmon DNA (SDNA) thin films, doped with 3 combinations of double divalent metal ions (M2+)-doped groups (Co2+-Ni2+, Cu2+-Co2+, and Cu2+-Ni2+) and single combination of a triple M2+-doped group (Cu2+-Ni2+-Co2+) at various concentrations of M2+ ([M2+]). We evaluated the optimum concentration of M2+ ([M2+]O) (the phase of M2+-doped DX DNA lattices changed from crystalline (up to ([M2+]O) to amorphous (above [M2+]O)) and measured the current, absorbance, and photoluminescent characteristics of multiple M2+-doped SDNA thin films. Phase transitions (visualized in phase diagrams theoretically as well as experimentally) from crystalline to amorphous for double (Co2+-Ni2+, Cu2+-Co2+, and Cu2+-Ni2+) and triple (Cu2+-Ni2+-Co2+) dopings occurred between 0.8 mM and 1.0 mM of Ni2+ at a fixed 0.5 mM of Co2+, between 0.6 mM and 0.8 mM of Co2+ at a fixed 3.0 mM of Cu2+, between 0.6 mM and 0.8 mM of Ni2+ at a fixed 3.0 mM of Cu2+, and between 0.6 mM and 0.8 mM of Co2+ at fixed 2.0 mM of Cu2+ and 0.8 mM of Ni2+, respectively. The overall behavior of the current and photoluminescence showed increments as increasing [M2+] up to [M2+]O, then decrements with further increasing [M2+]. On the other hand, absorbance at 260 nm showed the opposite behavior. Multiple M2+-doped DNA thin films can be used in specific devices and sensors with enhanced optoelectric characteristics and tunable multi-functionalities.

  17. Investigation of structural and luminescent properties of Ce{sup 3+}/Mn{sup 2+} ions-doped Ca{sub 5}(PO{sub 4}){sub 3}F

    SciT

    Zhang, Lei; Fu, Zuoling, E-mail: zlfu@jlu.edu.cn; Wu, Zhijian

    Graphical abstract: The structural and luminescent properties FAP: Ce{sup 3+} and FAP: Ce{sup 3+}, Mn{sup 2+} were investigated in detail by the spectral measurement and theoretical calculation. The emission of Ce{sup 3+} is fitted by two Gaussian functions dashed lines in wavenumber to further confirm the Ce{sup 3+} ion simultaneously occupy the 4f and 6h sites Ca{sub 5}(PO{sub 4})F host. - Highlights: • A simple hydrothermal method has been used to prepare Ca{sub 5}(PO{sub 4}){sub 3}F: Ce{sup 3+}, Mn{sup 2+} powders with structural and luminescent analysis. • The emission of Ce{sup 3+} is fitted by two Gaussian functions to confirmmore » the Ce{sup 3+} ion simultaneously to occupy the 4f and 6h sites in Ca{sub 5}(PO{sub 4}){sub 3}F host. • Due to an efficient energy transfer, the existence of Ce{sup 3+} (sensitizer) can dramatically enhance the green emission of Mn{sup 2+} (activator) in co-doped samples. - Abstract: Ce{sup 3+}/Mn{sup 2+} ions-doped oxyapatite calcium fluorapatite [Ca{sub 5}(PO{sub 4}){sub 3}F, FAP] has been successfully synthesized by a facile one-step hydrothermal method. The luminescent properties of Ce{sup 3+}- and Ce{sup 3+}/Mn{sup 2+}- activated FAP phosphors were investigated using the photoluminescence (PL) and photoluminescence excitation (PLE) spectra. The emission of Ce{sup 3+} was fitted by two Gaussian functions with dashed lines in wavenumber to confirm the Ce{sup 3+} ion simultaneously to occupy the 4f and 6h sites in Ca{sub 5}(PO{sub 4}){sub 3}F host, which was consistent with the calculated results of crystal field based on chemical bond theory. In addition, the existence of Ce{sup 3+} (sensitizer) can dramatically enhance the green emission of Mn{sup 2+} (activator) in Ce{sup 3+}/Mn{sup 2+} ions co-doped samples due to an efficient energy transfer from Ce{sup 3+} to Mn{sup 2+}. All of these results could help us understand the site assignments and optical properties of the rare earth ions doped in hexagonal Ca{sub 5}(PO

  18. Dispersive heterodyne probing method for laser frequency stabilization based on spectral hole burning in rare-earth doped crystals.

    PubMed

    Gobron, O; Jung, K; Galland, N; Predehl, K; Le Targat, R; Ferrier, A; Goldner, P; Seidelin, S; Le Coq, Y

    2017-06-26

    Frequency-locking a laser to a spectral hole in rare-earth doped crystals at cryogenic temperature has been shown to be a promising alternative to the use of high finesse Fabry-Perot cavities when seeking a very high short term stability laser (M. J. Thorpe et al., Nature Photonics 5, 688 (2011)). We demonstrate here a novel technique for achieving such stabilization, based on generating a heterodyne beat-note between a master laser and a slave laser whose dephasing caused by propagation near a spectral hole generate the error signal of the frequency lock. The master laser is far detuned from the center of the inhomogeneous absorption profile, and therefore exhibits only limited interaction with the crystal despite a potentially high optical power. The demodulation and frequency corrections are generated digitally with a hardware and software implementation based on a field-programmable gate array and a Software Defined Radio platform, making it straightforward to address several frequency channels (spectral holes) in parallel.

  19. Up-conversion in rare-earth doped micro-particles applied to new emissive two-dimensional displays

    NASA Astrophysics Data System (ADS)

    Milliez, Anne Janet

    Up-conversion (UC) in rare-earth co-doped fluorides to convert diode laser light in the near infrared to red, green and blue visible light is applied to make possible high performance emissive displays. The infrared-to-visible UC in the materials we study is a sequential form of non-linear two photon absorption in which a strong absorbing constituent absorbs two low energy photons and transfers this energy to another constituent which emits visible light. Some of the UC emitters' most appealing characteristics for displays are: a wide color gamut with very saturated colors, very high brightness operation without damage to the emitters, long lifetimes and efficiencies comparable to those of existing technologies. Other advantages include simplicity of fabrication, versatility of operating modes, and the potential for greatly reduced display weight and depth. Thanks to recent advances in material science and diode laser technology at the excitation wavelength, UC selected materials can be very efficient visible emitters. However, optimal UC efficiencies strongly depend on chosing proper operating conditions. In this thesis, we studied the conditions required for optimization. We demonstrated that high efficiency UC depends on high pump irradiance, low temperature and low scattering. With this understanding we can predict how to optimally use UC emitters in a wide range of applications. In particular, we showed how our very efficient UC emitters can be applied to make full color displays and very efficient white light sources.

  20. Magnetocaloric effect in heavy rare-earth elements doped Fe-based bulk metallic glasses with tunable Curie temperature

    SciT

    Li, Jiawei; Huo, Juntao; Chang, Chuntao, E-mail: ctchang@nimte.ac.cn, E-mail: dujun@nimte.ac.cn

    2014-08-14

    The effects of heavy rare earth (RE) additions on the Curie temperature (T{sub C}) and magnetocaloric effect of the Fe-RE-B-Nb (RE = Gd, Dy and Ho) bulk metallic glasses were studied. The type of dopping RE element and its concentration can easily tune T{sub C} in a large temperature range of 120 K without significantly decreasing the magnetic entropy change (ΔS{sub M}) and refrigerant capacity (RC) of the alloys. The observed values of ΔS{sub M} and RC of these alloys compare favorably with those of recently reported Fe-based metallic glasses with enhanced RC compared to Gd{sub 5}Ge{sub 1.9}Si{sub 2}Fe{sub 0.1}. The tunable T{submore » C} and large glass-forming ability of these RE doped Fe-based bulk metallic glasses can be used in a wide temperature range with the final required shapes.« less

  1. Thermochemistry of rare earth doped uranium oxides LnxU1-xO2-0.5x+y (Ln = La, Y, Nd)

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Navrotsky, Alexandra

    2015-10-01

    Lanthanum, yttrium, and neodymium doped uranium dioxide samples in the fluorite structure have been synthesized, characterized in terms of metal ratio and oxygen content, and their enthalpies of formation measured by high temperature oxide melt solution calorimetry. For oxides doped with 10-50 mol % rare earth (Ln) cations, the formation enthalpies from constituent oxides (LnO1.5, UO2 and UO3 in a reaction not involving oxidation or reduction) become increasingly exothermic with increasing rare earth content, while showing no significant dependence on the varying uranium oxidation state. The oxidation enthalpy of LnxU1-xO2-0.5x+y is similar to that of UO2 to UO3 for all three rare earth doped systems. Though this may suggest that the oxidized uranium in these systems is energetically similar to that in the hexavalent state, thermochemical data alone can not constrain whether the uranium is present as U5+, U6+, or a mixture of oxidation states. The formation enthalpies from elements calculated from the calorimetric data are generally consistent with those from free energy measurements.

  2. The effect of MgO on the optical properties of lithium sodium borate doped with Cu+ ions

    NASA Astrophysics Data System (ADS)

    Alajerami, Yasser Saleh Mustafa; Hashim, Suhairul; Hassan, Wan Muhamad Saridan Wan; Ramli, Ahmad Termizi; Saleh, Muneer Aziz

    2013-04-01

    The current work presented the photoluminescence (PL) properties of a new glass system, which are reported for the first time. Based on the attractive properties of borate glass, a mixture of boric acid (70-x mol %) modified with lithium (20 mol %) and sodium carbonate (10 mol %) was prepared. The current study illustrated the effect of dopant and co-dopant techniques on the lithium sodium borate (LNB). Firstly, 0.1 mol % of copper ions doped with LNB was excited at 610 nm. The emission spectrum showed two prominent peaks in the violet region (403 and 440 nm). Then, we remarked the effect of adding different concentration of MgO on the optical properties of LNB. The results showed the great effect of magnesium oxide on the PL intensities (enhanced more than two times). Moreover, an obvious shifting has been defined toward the blue region (440 → 475 nm). The up-conversion optical properties were observed in all emission spectra. This enhancement is contributed to the energy transfer from MgO ions to monovalent Cu+ ion. It is well known that magnesium oxide alone generates weak emission intensity, but during this increment the MgO act as an activator (co-doped) for Cu+ ions. Finally, energy band gap, density, ion concentration, molar volume, Polaron radius and inter-nuclear distance all were measured for the current samples. The current samples were subjected to XRD for amorphous confirmation and IR for glass characterization before and after dopants addition. Finally, some of significant physical and optical parameters were also calculated.

  3. Optical parameters and dispersion behavior of potassium magnesium chloride sulfate single crystals doped with Co+2 ions

    NASA Astrophysics Data System (ADS)

    Abu El-Fadl, A.; Abd-Elsalam, A. M.

    2018-05-01

    Single crystals of potassium magnesium chloride sulfate (KMCS) doped with cobalt ions were grown by slow cooling method. Powder XRD study confirmed the monoclinic structure of the grown crystals. The functional group vibrations were checked through FTIR spectroscopy measurements. In optical studies, the absorbance behavior of the crystals and their optical energy gap were established by Tauc plot. The refractive index, the extinction coefficient and other optical constants were calculated for the grown crystals. The normal dispersion of the refractive index was analyzed according to single oscillator Sellmeier's model. The Urbach's rule was applied to analyze the localized states density in the forbidden gap.

  4. Limitations of Electromagnetic Ion Cyclotron Wave Observations in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Hwang, Junga; Kim, Hyangpyo; Park, Jaeheung; Lee, Jaejin

    2018-03-01

    Pc1 pulsations are geomagnetic fluctuations in the frequency range of 0.2 to 5 Hz. There have been several observations of Pc1 pulsations in low earth orbit by MAGSAT, DE-2, Viking, Freja, CHAMP, and SWARM satellites. However, there has been a clear limitation in resolving the spatial and temporal variations of the pulsation by using a single-point observation by a single satellite. To overcome such limitations of previous observations, a new space mission was recently initiated, using the concept of multi-satellites, named the Small scale magNetospheric and Ionospheric Plasma Experiments (SNIPE). The SNIPE mission consists of four nanosatellites ( 10 kg), which will be launched into a polar orbit at an altitude of 600 km (TBD) in 2020. Four satellites will be deployed in orbit, and the distances between each satellite will be controlled from 10 to 1,000 km by a highend formation-flying algorithm. One of the possible science targets of the SNIPE mission is observing electromagnetic ion cyclotron (EMIC) waves. In this paper, we report on examples of observations, showing the limitations of previous EMIC observations in low earth orbit, and suggest possibilities to overcome those limitations through a new mission.

  5. Antiferromagnetic coupling between rare earth ions and semiquinones in a series of 1:1 complexes.

    PubMed

    Caneschi, Andrea; Dei, Andrea; Gatteschi, Dante; Poussereau, Sandrine; Sorace, Lorenzo

    2004-04-07

    We use the strategy of diamagnetic substitution for obtaining information on the crystal field effects in paramagnetic rare earth ions using the homologous series of compounds with the diamagnetic tropolonato ligand, Ln(Trp)(HBPz(3))(2), and the paramagnetic semiquinone ligand, Ln(DTBSQ)(HBPz(3))(2), (DTBSQ = 3,5-di-tert-butylsemiquinonato, Trp = tropolonate, HBPz(3)= hydrotrispyrazolylborate) for Ln = Sm(iii), Eu(iii), Gd(iii), Tb(iii), Dy(iii), Ho(iii), Er(iii) or Yb(iii). The X-ray crystal structure of a new form of tropolonate derivative is presented, which shows, as expected, a marked similarity with the structure of the semiquinonate derivative. The Ln(Trp)(HBPz(3))(2) derivatives were then used as a reference for the qualitative determination of crystal field effects in the exchange coupled semiquinone derivatives. Through magnetisation and susceptibility measurements this empirical diamagnetic substitution method evidenced for Er(iii), Tb(iii), Dy(iii) and Yb(iii) derivatives a dominating antiferromagnetic coupling. The increased antiferromagnetic contribution compared to other radical-rare earth metal complexes formed by nitronyl nitroxide ligands may be related to the increased donor strength of the semiquinone ligand.

  6. General Synthesis of Transition-Metal Oxide Hollow Nanospheres/Nitrogen-Doped Graphene Hybrids by Metal-Ammine Complex Chemistry for High-Performance Lithium-Ion Batteries.

    PubMed

    Chen, Jiayuan; Wu, Xiaofeng; Gong, Yan; Wang, Pengfei; Li, Wenhui; Mo, Shengpeng; Peng, Shengpan; Tan, Qiangqiang; Chen, Yunfa

    2018-02-09

    We present a general and facile synthesis strategy, on the basis of metal-ammine complex chemistry, for synthesizing hollow transition-metal oxides (Co 3 O 4 , NiO, CuO-Cu 2 O, and ZnO)/nitrogen-doped graphene hybrids, potentially applied in high-performance lithium-ion batteries. The oxygen-containing functional groups of graphene oxide play a prerequisite role in the formation of hollow transition-metal oxides on graphene nanosheets, and a significant hollowing process occurs only when forming metal (Co 2+ , Ni 2+ , Cu 2+ , or Zn 2+ )-ammine complex ions. Moreover, the hollowing process is well correlated with the complexing capacity between metal ions and NH 3 molecules. The significant hollowing process occurs for strong metal-ammine complex ions including Co 2+ , Ni 2+ , Cu 2+ , and Zn 2+ ions, and no hollow structures formed for weak and/or noncomplex Mn 2+ and Fe 3+ ions. Simultaneously, this novel strategy can also achieve the direct doping of nitrogen atoms into the graphene framework. The electrochemical performance of two typical hollow Co 3 O 4 or NiO/nitrogen-doped graphene hybrids was evaluated by their use as anodic materials. It was demonstrated that these unique nanostructured hybrids, in contrast with the bare counterparts, solid transition-metal oxides/nitrogen-doped graphene hybrids, perform with significantly improved specific capacity, superior rate capability, and excellent capacity retention. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Ion transport and loss in the earth's quiet ring current. I - Data and standard model

    NASA Technical Reports Server (NTRS)

    Sheldon, R. B.; Hamilton, D. C.

    1993-01-01

    A study of the transport and loss of ions in the earth's quiet time ring current, in which the standard radial diffusion model developed for the high-energy radiation belt particles is compared with the measurements of the lower-energy ring current ions, is presented. The data set provides ionic composition information in an energy range that includes the bulk of the ring current energy density, 1-300 keV/e. Protons are found to dominate the quiet time energy density at all altitudes, peaking near L of about 4 at 60 keV/cu cm, with much smaller contributions from O(+) (1-10 percent), He(+) (1-5 percent), and He(2+) (less than 1 percent). A minimization procedure is used to fit the amplitudes of the standard electric radial diffusion coefficient, yielding 5.8 x 10 exp -11 R(E-squared)/s. Fluctuation ionospheric electric fields are suggested as the source of the additional diffusion detected.

  8. Highly sensitive and selective spectrofluorimetric determination of metoclopramide hydrochloride in pharmaceutical tablets and serum samples using Eu3+ ion doped in sol-gel matrix.

    PubMed

    Attia, M S; Aboaly, M M

    2010-06-30

    A simple, sensitive and selective spectrofluorimetric method for the determination of Metoclopramide hydrochloride (MCP) is developed. The MCP can remarkably enhances the luminescence intensity of the Eu(3+) ion doped in sol-gel matrix at lambda(ex)=380 nm in DMSO at pH 8.7. The intensity of the emission band of Eu(3+) ion doped in sol-gel matrix increases due to energy transfer from MCP to Eu(3+) in the excited state. The enhancement of the emission band of Eu(3+) ion doped in sol-gel matrix at 617 nm was found to be directly proportional to the concentration of MCP with a dynamic range of 5 x 10(-9) - 1.0 x 10(-6) mol L(-1) and detection limit of 2.2 x10(-11) mol L(-1). Copyright 2010 Elsevier B.V. All rights reserved.

  9. Low temperature deactivation of Ge heavily n-type doped by ion implantation and laser thermal annealing

    NASA Astrophysics Data System (ADS)

    Milazzo, R.; Impellizzeri, G.; Piccinotti, D.; De Salvador, D.; Portavoce, A.; La Magna, A.; Fortunato, G.; Mangelinck, D.; Privitera, V.; Carnera, A.; Napolitani, E.

    2017-01-01

    Heavy doping of Ge is crucial for several advanced micro- and optoelectronic applications, but, at the same time, it still remains extremely challenging. Ge heavily n-type doped at a concentration of 1 × 1020 cm-3 by As ion implantation and melting laser thermal annealing (LTA) is shown here to be highly metastable. Upon post-LTA conventional thermal annealing As electrically deactivates already at 350 °C reaching an active concentration of ˜4 × 1019 cm-3. No significant As diffusion is detected up to 450 °C, where the As activation decreases further to ˜3 × 1019 cm-3. The reason for the observed detrimental deactivation was investigated by Atom Probe Tomography and in situ High Resolution X-Ray Diffraction measurements. In general, the thermal stability of heavily doped Ge layers needs to be carefully evaluated because, as shown here, deactivation might occur at very low temperatures, close to those required for low resistivity Ohmic contacting of n-type Ge.

  10. Large-Area Carbon Nanosheets Doped with Phosphorus: A High-Performance Anode Material for Sodium-Ion Batteries.

    PubMed

    Hou, Hongshuai; Shao, Lidong; Zhang, Yan; Zou, Guoqiang; Chen, Jun; Ji, Xiaobo

    2017-01-01

    Large-area phosphorus-doped carbon nanosheets (P-CNSs) are first obtained from carbon dots (CDs) through self-assembly driving from thermal treatment with Na catalysis. This is the first time to realize the conversion from 0D CDs to 2D nanosheets doped with phosphorus. The sodium storage behavior of phosphorus-doped carbon material is also investigated for the first time. As anode material for sodium-ion batteries (SIBs), P-CNSs exhibit superb performances for electrochemical storage of sodium. When cycled at 0.1 A g -1 , the P-CNSs electrode delivers a high reversible capacity of 328 mAh g -1 , even at a high current density of 20 A g -1 , a considerable capacity of 108 mAh g -1 can still be maintained. Besides, this material also shows excellent cycling stability, at a current density of 5 A g -1 , the reversible capacity can still reach 149 mAh g -1 after 5000 cycles. This work will provide significant value for the development of both carbon materials and SIBs anode materials.

  11. Influence of Sn ion doping on the photocatalytic performance of V2O5 nanorods prepared by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Rajeshwari, S.; Santhosh Kumar, J.; Rajendrakumar, R. T.; Ponpandian, N.; Thangadurai, P.

    2018-02-01

    Pure and different concentrations of Sn4+ doped V2O5 (Sn:V2O5) nanorods were synthesized by hydrothermal method. The Sn:V2O5 nanorods obtained were orthorhombic in structure. No secondary phase was observed up to 10% of Sn doping, but beyond that, there evolved a secondary phase of SnO2. Microstructural analysis revealed the morphology of V2O5 as nanorods and platelets like structure. Presence of V, O and Sn elements in the samples was confirmed by energy dispersive spectroscopy. The V2O5 nanorods have shown a strong absorption in the visible region and the band gap energy was obtained to be varying from 2.21 to 2.26 eV as a function of Sn ion doping. Photocatalytic studies on methylene blue (MB) under visible light irradiation showed that the 3% Sn:V2O5 had effectively degraded MB up to a maximum degradation of 96% and further increase in Sn content had decreased the photodegradation due to higher recombination rate of photogenerated electrons. The mechanism of photodegradation was completely understood and the OH· radicals have played a dominant role in the photodegradation of the organic dyes.

  12. Chemical bonding between antimony and ionic liquid-derived nitrogen-doped carbon for sodium-ion battery anode

    NASA Astrophysics Data System (ADS)

    Xu, Xin; Si, Ling; Zhou, Xiaosi; Tu, Fengzhang; Zhu, Xiaoshu; Bao, Jianchun

    2017-05-01

    Antimony has received a great deal of attention as a promising anode material for sodium-ion batteries (SIBs) due to its high theoretical capacity of 660 mAh g-1. However, this application is significantly hampered by inherent large volume change and sluggish kinetics. To address these issues, an antimony-cyano-based ionic liquid-derived nitrogen-doped carbon (Sbsbnd CNC) hybrid is proposed and synthesized by ball-milling and subsequent pyrolysis treatment. As an anode material for SIBs, the as-synthesized Sbsbnd CNC hybrid delivers reversible capacities of 475 mAh g-1 at a current density of 100 mA g-1 and 203 mAh g-1 at 5000 mA g-1, and a 92.4% capacity retention based on the first-cycle capacity after 150 cycles at 100 mA g-1. Using ex situ X-ray photoelectron spectroscopy and elemental mapping techniques, we attribute the good structural integrity to the formation of Sbsbnd Nsbnd C bonds between Sb and the cyano-based ionic liquid-derived N-doped carbon matrix. Moreover, the presence of N-doped carbon network in the hybrid material serves as a robust protective cover and an electrical highway, buffering the substantial volume expansion of Sb nanoparticles and ensuring the fast electron transport for stable cycling operation.

  13. Improved electrochemical performance of boron-doped SiO negative electrode materials in lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Woo, Jihoon; Baek, Seong-Ho; Park, Jung-Soo; Jeong, Young-Min; Kim, Jae Hyun

    2015-12-01

    We introduce a one-step process that consists of thermal disproportionation and impurity doping to enhance the reversible capacity and electrical conductivity of silicon monoxide (SiO)-based negative electrode materials in Li-ion batteries. Transmission electron microscope (TEM) results reveal that thermally treated SiO at 900 °C (H-SiO) consists of uniformly dispersed nano-crystalline Si (nc-Si) in an amorphous silicon oxide (SiOx) matrix. Compared to that of prinstine SiO, the electrochemical performance of H-SiO shows improved specific capacity, due mainly to the increased reversible capacity by nc-Si and to the reduced volume expansion by thermally disproportionated SiOx matrix. Further electrochemical improvements can be obtained by boron-doping on SiO (HB-SiO) using solution dopant during thermal disproportionation. HB-SiO electrode without carbon coating exhibits significantly enhanced specific capacity superior to that of undoped H-SiO electrode, having 947 mAh g-1 at 0.5C rate and excellent capacity retention of 93.3% over 100 cycles. Electrochemical impedance spectroscopy (EIS) measurement reveals that the internal resistance of the HB-SiO electrode is significantly reduced by boron doping.

  14. Unambiguously identifying spin states of transition-metal ions in the Earth (Invited)

    NASA Astrophysics Data System (ADS)

    Hsu, H.

    2010-12-01

    The spin state of a transition-metal ion in crystalline solids, defined by the number of unpaired electrons in the ion’s incomplete 3d shell, may vary with many factors, such as temperature, pressure, strain, and the local atomic configuration, to name a few. Such a phenomenon, known as spin-state crossover, plays a crucial role in spintronic materials. Recently, the pressure-induced spin-state crossover in iron-bearing minerals has been recognized to affect the minerals’ structural and elastic properties. However, the detailed mechanism of such crossover in iron-bearing magnesium silicate perovskite, the most abundant mineral in the Earth, remains unclear. A significant part of this confusion arises from the difficulty in reliably extracting the spin state from experiments. For the same reason, the thermally-induced spin-state crossover in lanthanum cobaltite (LaCoO3) has been controversial for more than four decades. In this talk, I will discuss how first-principle calculations can help clarifying these long-standing controversies. In addition to the total energy, equation of state, and elastic properties of each spin state, first-principle calculations also predict the electric field gradient (EFG) at the nucleus of each transition-metal ion. Our calculations showed that the nuclear EFG, a quantity that can be measured via Mössbauer or nuclear magnetic resonance (NMR) spectroscopy, depends primarily on the spin state, irrespective of the concentration or configuration of transition-metal ions. Such robustness makes EFG a unique fingerprint to identify the spin state. The combination of first-principle calculations and Mössbauer/NMR spectroscopy can therefore be a reliable and efficient approach in tackling spin-state crossover problems in the Earth. This work was primarily supported by the MRSEC Program of NSF under Awards Number DMR-0212302 and DMR-0819885, and partially supported by NSF under ATM-0428774 (V-Lab), EAR-1019853, and EAR-0810272. The

  15. MAVEN-Measured Meteoritic Ions on Mars - Tracers of Lower Ionosphere Processes With and Without Analogues On Earth

    NASA Astrophysics Data System (ADS)

    Benna, M.; Grebowsky, J. M.; Collinson, G.; Plane, J. M. C.; Mitchell, D.; Srivastava, N.

    2017-12-01

    MAVEN observations of meteoritic metal ion populations during "deep dip" campaigns at Mars have revealed unique non-Earth like behavior that are not yet understood. These deep dip campaigns (6 so far) consisted each of more than a score of repeated orbits through the Martian molecular-ion-dominated lower ionosphere, whose terrestrial parallel (Earth's E-region) has been rather sparcely surveyed in situ by sounding rockets. In regions of weak Mars magnetic fields, MAVEN found ordered exponentially decreasing metal ion concentrations above the altitude of peak meteor ablation. Such an ordered trend has never been observed on Earth. Isolated anomalous high-altitude layers in the metal ion are also encountered, typically on deep dip campaigns in the southern hemisphere where large localized surface remanent magnetic fields prevail. The source of these anomalous layers is not yet evident, although the occurrences of some high-altitude metal ion enhancements were in regions with measured perturbed magnetic fields, indicative of localized electrical currents. Further investigation shows that those currents are also sometimes associated with superthermal/energetic electron bursts offering evidence that that impact ionization of neutral metal populations persisting at high altitudes are the source of metal ion enhancement - a rather difficult assumption to accept far above the ablation region where the metal neutrals are deposited. The relationship of the anomalous layers to the coincident electron populations as well as to the orientation of the magnetic fields which can play a role in the neutral wind generated ion convergences as on Earth is investigated.

  16. Morphological, Raman, electrical and dielectric properties of rare earth doped X-type hexagonal ferrites

    NASA Astrophysics Data System (ADS)

    Majeed, Abdul; Khan, Muhammad Azhar; ur Raheem, Faseeh; Ahmad, Iftikhar; Akhtar, Majid Niaz; Warsi, Muhammad Farooq

    2016-12-01

    The influence of rare-earth metals (La, Nd, Gd, Tb, Dy) on morphology, Raman, electrical and dielectric properties of Ba2NiCoRExFe28-xO46 ferrites were studied. The scanning electron microscopy (SEM) exhibited the platelet like structure of these hexagonal ferrites. The surface morphology indicated the formation of ferrite grains in the nano-regime scale. The bands obtained at lower wave number may be attributed to the metal-oxygen vibration at octahedral site which confirm the development of hexagonal phase of these ferrites. The resonance peaks were observed in dielectric constant, dielectric loss factor and quality factor versus frequency graphs. These dielectric parameters indicate that these ferrites nano-materials are potential candidates in the high frequency applications. The enhancement in DC electric resistivity from 2.48×108 to 1.20×109 Ω cm indicates that the prepared materials are beneficial for decreasing the eddy current losses at high frequencies and for the fabrication of multilayer chip inductor (MLCI) devices.

  17. ZIF-8 Derived, Nitrogen-Doped Porous Electrodes of Carbon Polyhedron Particles for High-Performance Electrosorption of Salt Ions.

    PubMed

    Liu, Nei-Ling; Dutta, Saikat; Salunkhe, Rahul R; Ahamad, Tansir; Alshehri, Saad M; Yamauchi, Yusuke; Hou, Chia-Hung; Wu, Kevin C-W

    2016-07-12

    Three-dimensional (3-D) ZIF-8 derived carbon polyhedrons with high nitrogen (N) content, (denoted as NC-800) are synthesized for their application as high-performance electrodes in electrosorption of salt ions. The results showed a high specific capacitance of 160.8 F·g(-1) in 1 M NaCl at a scan rate of 5 mV·s(-1). Notably, integration of 3-D mesopores and micropores in NC-800 achieves an excellent capacitive deionization (CDI) performance. The electrosorption of salt ions at the electrical double layer is enhanced by N-doping at the edges of a hexagonal lattice of NC-800. As evidenced, when the initial NaCl solution concentration is 1 mM, the resultant NC-800 exhibits a remarkable CDI potential with a promising salt electrosorption capacity of 8.52 mg·g(-1).

  18. ZIF-8 Derived, Nitrogen-Doped Porous Electrodes of Carbon Polyhedron Particles for High-Performance Electrosorption of Salt Ions

    PubMed Central

    Liu, Nei-Ling; Dutta, Saikat; Salunkhe, Rahul R.; Ahamad, Tansir; Alshehri, Saad M.; Yamauchi, Yusuke; Hou, Chia-Hung; Wu, Kevin C.-W.

    2016-01-01

    Three-dimensional (3-D) ZIF-8 derived carbon polyhedrons with high nitrogen (N) content, (denoted as NC-800) are synthesized for their application as high-performance electrodes in electrosorption of salt ions. The results showed a high specific capacitance of 160.8 F·g−1 in 1 M NaCl at a scan rate of 5 mV·s−1. Notably, integration of 3-D mesopores and micropores in NC-800 achieves an excellent capacitive deionization (CDI) performance. The electrosorption of salt ions at the electrical double layer is enhanced by N-doping at the edges of a hexagonal lattice of NC-800. As evidenced, when the initial NaCl solution concentration is 1 mM, the resultant NC-800 exhibits a remarkable CDI potential with a promising salt electrosorption capacity of 8.52 mg·g−1. PMID:27404086

  19. Synthesis and structural characterization of Co2+ ions doped ZnO nanopowders by solid state reaction through sonication

    NASA Astrophysics Data System (ADS)

    Babu, B.; Rama Krishna, Ch.; Venkata Reddy, Ch.; Pushpa Manjari, V.; Ravikumar, R. V. S. S. N.

    2013-05-01

    Cobalt ions doped zinc oxide nanopowder was prepared at room temperature by a novel and simple one step solid-state reaction method through sonication in the presence of a suitable surfactant Sodium Lauryl Sulphate (SLS). The prepared powder was characterized by various spectroscopic techniques. Powder XRD data revealed that the crystal structure belongs to hexagonal and its average crystallite size was evaluated. From optical absorption data, crystal fields (Dq), inter-electronic repulsion parameters (B, C) were evaluated. By correlating optical and EPR spectral data, the site symmetry of Co2+ ion in the host lattice was determined as octahedral. Photoluminescence spectra exhibited the emission bands in ultraviolet and blue regions. The CIE chromaticity coordinates are also evaluated from the emission spectrum. FT-IR spectra showed the characteristic vibrational bands of Znsbnd O.

  20. Indirect ultraviolet detection of alkaline earth metal ions using an imidazolium ionic liquid as an ultraviolet absorption reagent in ion chromatography.

    PubMed

    Liu, Yong-Qiang; Yu, Hong

    2017-04-01

    A convenient and versatile method was developed for the separation and detection of alkaline earth metal ions by ion chromatography with indirect UV detection. The chromatographic separation of Mg 2+ , Ca 2+ , and Sr 2+ was performed on a carboxylic acid base cation exchange column using imidazolium ionic liquid/acid as the mobile phase, in which the imidazolium ionic liquid acted as an UV-absorption reagent. The effects of imidazolium ionic liquids, detection wavelength, acids in the mobile phase, and column temperature on the retention of Mg 2+ , Ca 2+ , and Sr 2+ were investigated. The main factors influencing the separation and detection were the background UV absorption reagent and the concentration of hydrogen ion in ion chromatography with indirect UV detection. The successful separation and detection of Mg 2+ , Ca 2+ , and Sr 2+ within 14 min were achieved using the selected chromatographic conditions, and the detection limits (S/N = 3) were 0.06, 0.12, and 0.23 mg/L, respectively. A new separation and detection method of alkaline earth metal ions by ion chromatography with indirect UV detection was developed, and the application range of ionic liquids was expanded. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Promoting effect of alkaline earth metal doping on catalytic activity of HC and NOx conversion over Pd-only three-way catalyst.

    PubMed

    Yang, Linyan; Lin, Siyu; Yang, Xue; Fang, Weimin; Zhou, Renxian

    2014-08-30

    The influence of alkaline earth metal (M=Mg, Ca, Sr and Ba) promoter on the structural/textural properties of Ce0.67Zr0.33O2 (designated as CZ) and the catalytic behavior of its supported Pd-only three-way catalyst (Pd/CZM) have been investigated. The results show that the modification with alkaline earth metal obviously improves the catalytic activity for hydrocarbon (HC) and nitrogen oxides (NOx) conversion, especially the introduction of Ba. Furthermore, the operation window of the promoted catalysts has also been widened. The doping of alkaline earth metal leads to the formation of more homogeneous Ce-Zr-M ternary solid solution with higher surface area and smaller crystallite size, and the corresponding Pd/CZM catalysts present improved reducibility of PdO species. The modification with Ca, Sr and Ba improves the thermal aging resistance, especially Ba. DRIFTS results reveal that the doping of alkaline earth metal enhances the oxygen and electron transfer ability and favors the dissociation of NO, which promotes the activation and storage capacity of the acidic atoms like NOx, and leads to enhanced catalytic activity performance. Copyright © 2014 Elsevier B.V. All rights reserved.

  2. Earth

    2012-01-30

    Behold one of the more detailed images of the Earth yet created. This Blue Marble Earth montage shown above -- created from photographs taken by the Visible/Infrared Imager Radiometer Suite (VIIRS) instrument on board the new Suomi NPP satellite -- shows many stunning details of our home planet. The Suomi NPP satellite was launched last October and renamed last week after Verner Suomi, commonly deemed the father of satellite meteorology. The composite was created from the data collected during four orbits of the robotic satellite taken earlier this month and digitally projected onto the globe. Many features of North America and the Western Hemisphere are particularly visible on a high resolution version of the image. http://photojournal.jpl.nasa.gov/catalog/PIA18033

  3. Lead-free piezoelectrics: V3+ to V5+ ion conversion promoting the performances of V-doped Zinc Oxide.

    PubMed

    Laurenti, M; Castellino, M; Perrone, D; Asvarov, A; Canavese, G; Chiolerio, A

    2017-02-06

    Vanadium doped ZnO (VZO) thin films were grown by RF magnetron sputtering, starting from a ZnO:V ceramic target. The crystal structure, chemical composition, electric and piezoelectric properties of the films were investigated either on the as-grown thin films or after a post-deposition rapid thermal annealing (RTA) treatment performed at 600 °C for different lengths of time (1 and 5 min) in an oxygen atmosphere. Substitutional doping of Zn 2+ with V 3+ and V 5+ ions strongly deteriorated the hexagonal wurtzite ZnO structure of the as-grown thin films due to lattice distortion. The resulting slight amorphization led to a poor piezoelectric response and higher resistivity. After the RTA treatment, strong c-axis oriented VZO thin films were obtained, together with a partial conversion of the starting V 3+ ions into V 5+ . The improvement of the crystal structure and the stronger polarity of both V 3+ - O and V 5+ - O chemical bonds, together with the corresponding easier rotation under the application of an external electric field, positively affected the piezoelectric response and increased conductivity. This was confirmed by closed-loop butterfly piezoelectric curves, by a maximum d 33 piezoelectric coefficient of 85 pm·V -1 , and also by ferroelectric switching domains with a well-defined polarization hysteresis curve, featuring a residual polarization of 12.5 μC∙cm -2 .

  4. Porous Mn-doped cobalt oxide@C nanocomposite: a stable anode material for Li-ion rechargeable batteries

    NASA Astrophysics Data System (ADS)

    Kalubarme, Ramchandra S.; Jadhav, Sarika M.; Kale, Bharat B.; Gosavi, Suresh W.; Terashima, Chiaki; Fujishima, Akira

    2018-07-01

    Cobalt oxide is a transition metal oxide, well studied as an electrode material for energy storage applications, especially in supercapacitors and rechargeable batteries, due to its high charge storage ability. However, it suffers from low conductivity, which effectively hampers its long-term stability. In the present work, a simple strategy to enhance the conductivity of cobalt oxide is adopted to achieve stable electrochemical performance by means of carbon coating and Mn doping, via a simple and controlled, urea-assisted glycine-nitrate combustion process. Structural analysis of carbon coated Mn-doped Co3O4 (Mn-Co3O4@C) confirms the formation of nanoparticles (∼50 nm) with connected morphology, exhibiting spinel structure. The Mn-Co3O4@C electrode displays superior electrochemical performance as a Li-ion battery anode, delivering a specific capacity of 1250 mAh g‑1. Mn-Co3O4@C demonstrates excellent performance in terms of long-term stability, keeping charge storage ability intact even at high current rates due to the synergistic effects of fast kinetics—provided by enriched electronic conductivity, which allows ions to move freely to active sites and electrons from reaction sites to substrate during redox reactions—and high surface area combined with mesoporous architecture. The fully assembled battery device using Mn-Co3O4@C and standard LiCoO2 electrode shows 90% capacity retention over 100 cycles.

  5. Lead-free piezoelectrics: V3+ to V5+ ion conversion promoting the performances of V-doped Zinc Oxide

    PubMed Central

    Laurenti, M.; Castellino, M.; Perrone, D.; Asvarov, A.; Canavese, G.; Chiolerio, A.

    2017-01-01

    Vanadium doped ZnO (VZO) thin films were grown by RF magnetron sputtering, starting from a ZnO:V ceramic target. The crystal structure, chemical composition, electric and piezoelectric properties of the films were investigated either on the as-grown thin films or after a post-deposition rapid thermal annealing (RTA) treatment performed at 600 °C for different lengths of time (1 and 5 min) in an oxygen atmosphere. Substitutional doping of Zn2+ with V3+ and V5+ ions strongly deteriorated the hexagonal wurtzite ZnO structure of the as-grown thin films due to lattice distortion. The resulting slight amorphization led to a poor piezoelectric response and higher resistivity. After the RTA treatment, strong c-axis oriented VZO thin films were obtained, together with a partial conversion of the starting V3+ ions into V5+. The improvement of the crystal structure and the stronger polarity of both V3+ – O and V5+ – O chemical bonds, together with the corresponding easier rotation under the application of an external electric field, positively affected the piezoelectric response and increased conductivity. This was confirmed by closed-loop butterfly piezoelectric curves, by a maximum d33 piezoelectric coefficient of 85 pm·V−1, and also by ferroelectric switching domains with a well-defined polarization hysteresis curve, featuring a residual polarization of 12.5 μC∙cm−2. PMID:28165040

  6. Reaction of positronium with doped ions in silica-based glasses in the size determination of subnanometer structural open spaces

    NASA Astrophysics Data System (ADS)

    Inoue, K.; Kataoka, H.; Nagai, Y.; Hasegawa, M.; Kobayashi, Y.

    2013-10-01

    Positron annihilation spectroscopy is employed to estimate the size of subnanometer-scale open spaces in insulating materials. In most cases, the size is estimated from the lifetime of long-lived ortho-positronium (o-Ps) by pickoff annihilation using a simplified model. However, reactions of Ps with surrounding electrons other than the pickoff reaction, such as spin conversion or chemical reaction, could give a substantially underestimated size using the simplified model. In the present paper, we report that the size of the open spaces can be evaluated correctly by the angular correlation of positron annihilation radiation (ACAR) with a magnetic field using the spin-polarization effect on Ps formation, even if such reactions of Ps occur in the material. This method is applied to the subnanometer-scale structural open spaces of silica-based glass doped with Fe. We demonstrate the influence of the Ps reaction on size-estimation of the open spaces from the o-Ps lifetime. Furthermore, the type of reaction, whether spin conversion or chemical, is distinguished from the magnetic field dependence of the Ps self-annihilation component intensity in the ACAR spectra. The Ps reaction in silica-based glass doped with Fe is a chemical reaction (most likely oxidation) rather than spin conversion, with Fe ions. The chemical quenching rate with Fe ions is determined from the dependence of the o-Ps lifetime on the Fe content.

  7. Fabrication of high-performance metal ion doped iron oxide electrode for supercapacitor applications through a novel platform

    NASA Astrophysics Data System (ADS)

    Aghazadeh, Mustafa; Karimzadeh, Isa

    2017-10-01

    We provide a novel electrodeposition platform of undoped and Eu3+ doped iron oxide nanoparticles (Eu-IONPs) from an additive-free electrolyte containing Fe(NO3)3, FeCl2 and EuCl3. The prepared IONPs were analyzed using x-ray diffraction, field emission electron microscopy and energy-dispersive x-ray techniques, and the obtained data showed successful electrosynthesis of magnetite nanoparticles (size  ≈  10 nm) doped with about 10 wt% Eu3+ ions. The Eu-IONPs were used as supercapacitor electrode materials, and characterized by cyclic voltammetry and galvanostatic charge-discharge measurements. The as-synthesized Eu-IONPs exhibit remarkable pseudocapacitive activities including high specific capacitances of 212.5 and 153.2 F g-1 at 0.5 and 2 A g-1, respectively, and excellent cycling stabilities of 93.9% and 86.5% after 2000 discharging cycles. Furthermore, vibrational sample magnetometer data confirmed better superparamagnetic performance of Eu-IONPs (Ms  =  72.8 emu g-1, Mr  =  0.24 emu g-1 and H Ci  =  3.48 G) as compared with pure IONPs (Ms  =  51.92 emu g-1, Mr  =  0.95 emu g-1 and H Ci  =  14.62 G) due to exhibiting lower Mr and H Ci values. This novel synthetic platform of metal ion doped iron oxide is potentially a convenient way to fabricate high-performance iron oxide electrodes for energy storage systems.

  8. Doping of alkali, alkaline-earth, and transition metals in covalent-organic frameworks for enhancing CO2 capture by first-principles calculations and molecular simulations.

    PubMed

    Lan, Jianhui; Cao, Dapeng; Wang, Wenchuan; Smit, Berend

    2010-07-27

    We use the multiscale simulation approach, which combines the first-principles calculations and grand canonical Monte Carlo simulations, to comprehensively study the doping of a series of alkali (Li, Na, and K), alkaline-earth (Be, Mg, and Ca), and transition (Sc and Ti) metals in nanoporous covalent organic frameworks (COFs), and the effects of the doped metals on CO2 capture. The results indicate that, among all the metals studied, Li, Sc, and Ti can bind with COFs stably, while Be, Mg, and Ca cannot, because the binding of Be, Mg, and Ca with COFs is very weak. Furthermore, Li, Sc, and Ti can improve the uptakes of CO2 in COFs significantly. However, the binding energy of a CO2 molecule with Sc and Ti exceeds the lower limit of chemisorptions and, thus, suffers from the difficulty of desorption. By the comparative studies above, it is found that Li is the best surface modifier of COFs for CO2 capture among all the metals studied. Therefore, we further investigate the uptakes of CO2 in the Li-doped COFs. Our simulation results show that at 298 K and 1 bar, the excess CO2 uptakes of the Li-doped COF-102 and COF-105 reach 409 and 344 mg/g, which are about eight and four times those in the nondoped ones, respectively. As the pressure increases to 40 bar, the CO2 uptakes of the Li-doped COF-102 and COF-105 reach 1349 and 2266 mg/g at 298 K, respectively, which are among the reported highest scores to date. In summary, doping of metals in porous COFs provides an efficient approach for enhancing CO2 capture.

  9. Hydrothermal method of synthesis of rare-earth tantalates and niobates

    DOEpatents

    Nyman, May D; Rohwer, Lauren E.S.; Martin, James E

    2012-10-16

    A hydrothermal method of synthesis of a family of rare-earth Group 5 oxides, where the Group 5 oxide is a niobate or tantalate. The rare-earth Group 5 oxides can be doped with suitable emitter ions to form nanophosphors.

  10. A high energy and power sodium-ion hybrid capacitor based on nitrogen-doped hollow carbon nanowires anode

    NASA Astrophysics Data System (ADS)

    Li, Dongdong; Ye, Chao; Chen, Xinzhi; Wang, Suqing; Wang, Haihui

    2018-04-01

    The sodium ion hybrid capacitor (SHC) has been attracting much attention. However, the SHC's power density is significantly confined to a low level due to the sluggish ion diffusion in the anode. Herein, we propose to use an electrode with a high double layer capacitance as the anode in the SHC instead of insertion anodes. To this aim, nitrogen doped hollow carbon nanowires (N-HCNWs) with a high specific surface area are prepared, and the high capacitive contribution during the sodium ion storage process is confirmed by a series of electrochemical measurements. A new SHC consisting of a N-HCNW anode and a commercial active carbon (AC) cathode is fabricated for the first time. Due to the hybrid charge storage mechanism combining ion insertion and capacitive process, the as-fabricated SHC strikes a balance between the energy density and power density, a energy density of 108 Wh kg-1 and a power density of 9 kW kg-1 can be achieved, which overwhelms the electrochemical performances of most reported AC-based SHCs.

  11. Characterization and spectroscopic studies of multi-component calcium zinc bismuth phosphate glass ceramics doped with iron ions

    NASA Astrophysics Data System (ADS)

    Kumar, A. Suneel; Narendrudu, T.; Suresh, S.; Ram, G. Chinna; Rao, M. V. Sambasiva; Tirupataiah, Ch.; Rao, D. Krishna

    2018-04-01

    Glass ceramics with the composition 10CaF2-20ZnO-(15-x)Bi2O3-55P2O5:x Fe2O3(0≤x≤2.5) were synthesized by melt-quenching technique and heat treatment. These glass ceramics were characterized by XRD and SEM. Spectroscopic studies such as optical absorption, EPR were also carried out on these glass ceramics. From the absorption spectra the observed bands around 438 and 660nm are the octahedral transitions of Fe3+ (d5) ions and another band at about 536 nm is the tetrahedral transition of Fe3+ (d5) ions. The absorption spectrum also consist of a band around 991 nm and is attributed to the octahedral transition of Fe2+ ions. The EPR spectra of the prepared glass ceramics have exhibited two resonance signals one at g1=4.32 and another signal at g2=2.008. The observed decrease in band gap energy up to 2 mol% Fe2O3 doped glass ceramics is an evidence for the change of environment around iron ions and ligands from more covalent to less covalent (ionic) and induces higher concentration of NBOs which causes the depolymerization of the glass ceramic network.

  12. Photoinduced proton transfer coupled with energy transfer: Mechanism of sensitized luminescence of terbium ion by salicylic acid doped in polymer.

    PubMed

    Misra, Vinita; Mishra, Hirdyesh

    2008-06-28

    In the present work, excited state intramolecular proton transfer (ESIPT) in salicylic acid (SA) monoanion and subsequent sensitization of Tb(3+) ion in polyvinyl alcohol (PVA) have been studied. The study has been carried out both by steady state and time domain fluorescence measurement techniques at room temperature. It is found that the SA completely ionizes and exists as monoanion in PVA. It exhibits a large Stokes shifted blue emission (10 000 cm(-1)) due to ESIPT and shows a decay time of 6.85 ns. On the other hand, Tb(3+) ion shows a very weak green emission and a decay time of approximately 641 mus in PVA film. Upon incorporating Tb(3+) ion in SA doped PVA film, both intensity and decay time of SA decrease and sensitized emission from Tb(+3) ion along with 3.8 mus rise time is observed. Energy transfer is found to take place both from excited singlet as well as triplet states. A brief description of the properties of the present system from the viewpoint of luminescent solar collector material is addressed.

  13. Low temperature EPR investigation of Co2+ ion doped into rutile TiO2 single crystal: Experiments and simulations

    NASA Astrophysics Data System (ADS)

    Zerentürk, A.; Açıkgöz, M.; Kazan, S.; Yıldız, F.; Aktaş, B.

    2017-02-01

    In this paper, we present the results of X-band EPR spectra of Co2+ ion doped rutile (TiO2) which is one of the most promising memristor material. We obtained the angular variation of spectra in three mutually perpendicular planes at liquid helium (7-13 K) temperatures. Since the impurity ions have ½ effective spin and 7/2 nuclear spin, a relatively simple spin Hamiltonian containing only electronic Zeeman and hyperfine terms was utilized. Two different methods were used in theoretical analysis. Firstly, a linear regression analysis of spectra based on perturbation theory was studied. However, this approach is not sufficient for analyzing Co+2 spectra and leads to complex eigenvectors for G and A tensors due to large anisotropy of eigenvalues. Therefore, all spectra were analyzed again with exact diagonalization of spin Hamiltonian and the high accuracy eigenvalues and eigenvectors of G and A tensors were obtained by taking into account the effect of small sample misalignment from the exact crystallographic planes due to experimental conditions. Our results show that eigen-axes of g and A tensors are parallel to crystallographic directions. Hence, our EPR experiments proves that Co2+ ions substitute for Ti4+ ions in lattice. The obtained principal values of g tensor are gx=2.110(6), gy=5.890(2), gz=3.725(7) and principal values of hyperfine tensor are Ax=42.4, Ay=152.7, Az=26 (in 10-4/cm).

  14. 3D free-standing nitrogen-doped reduced graphene oxide aerogel as anode material for sodium ion batteries with enhanced sodium storage.

    PubMed

    Zhang, Jiao; Li, Chuanqi; Peng, Zhikun; Liu, Yushan; Zhang, Jianmin; Liu, Zhongyi; Li, Dan

    2017-07-07

    Sodium ion batteries have drawn extensive attentions for large-scale energy storage to replace lithium ion batteries primarily due to the natural abundance of sodium resource and low cost, but their energy density and electrochemical performance are hindered by the sluggish diffusion kinetics of sodium ion. Herein, free-standing nitrogen-doped graphene aerogel has been fabricated via hydrothermal reaction as the potential anode material for sodium ion batteries. The three dimensional porous network structure of the graphene aerogel provides sufficient interstitial space for sodium ion accommodation, allowing fast and reversible ion intercalation/de-intercalation. The nitrogen doping could introduce defects on the graphene sheets, making the feasible transport of large-sized sodium ion. Benefiting from the effective structure and nitrogen doping, the obtained material demonstrates high reversible capacities, good cycling performance (287.9 mA h g -1 after 200 cycles at a current density of 100 mA g -1 ), especially superior rate capability (151.9 mA h g -1 at a high current density of 5 A g -1 ).

  15. Influence of Nb doping on the phase transition properties of VO2 thin films prepared by ion beam co-sputtering deposition

    NASA Astrophysics Data System (ADS)

    Zhu, Huiqun; Li, Pengfei; Zhao, Lite; Liu, Jiahuan

    2016-03-01

    The Nb-doped VO2 thin films were successfully prepared on the glass substrates by ion beam co-sputtering at room temperature and post annealing under the air condition. The effects of the preparation processing and Nb doping on the thermal hysteresis loop and phase transition temperature of the VO2 thin films were analyzed by resistancetemperature measurement. The results show that Nb doping significantly changes the surface morphologies of VO2 thin films, and Nb-doped VO2 thin films exhibit VO2(002) preferred orientation growth with greatly improved crystallinity and orientation. Compared with pure VO2, the phase transition temperature of Nb-doped VO2 thin films drops to 40 ºC, and the width of thermal hysteresis loop narrows to 8 ºC. It is demonstrated that Nb-doped VO2 thin films prepared by ion beam co-sputtered at room temperature have an obvious thermal sensitive effect, and keep a good characteristic from metal to semiconductor phase transition.

  16. Multi-channel and porous SiO@N-doped C rods as anodes for high-performance lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Huang, Xiao; Li, Mingqi

    2018-05-01

    To improve the cycling stability and rate capability of SiO electrodes, multi-channel and porous SiO@N-doped C (mp-SiO@N-doped C) rods are fabricated by the combination of electrospinning and heat treatment with the assistance of poly(methyl methacrylate) (PMMA). During annealing, in-situ PMMA degradation and gasification lead to the formation of multi-channel structure and more pores. As anodes for lithium ion batteries, the mp-SiO@N-doped C rods exhibit excellent cycling stability. At a current density of 400 mA g-1, a discharge capacity of 806 mAh g-1 can be kept after 250 cycles, the retention of which is over than 100% versus the initial reversible capacity. Compared with the SiO@N-doped C rods synthesized without the help of PMMA, the mp-SiO@N-doped C rods exhibit more excellent rate capability. The excellent electrochemical performance is attributed to the special structure of the mp-SiO@N-doped C rods. In addition to the conductivity improved by carbon fibers, the multi-channel and porous structures not only make ions/electrons transfer and electrolyte diffusion easier, but also contribute to the structural stability of the electrodes.

  17. ZnMoO4:Er3+,Yb3+ phosphor with controlled morphology and enhanced upconversion through alkali ions doping

    NASA Astrophysics Data System (ADS)

    Luitel, Hom Nath; Chand, Rumi; Watari, Takanori

    2018-04-01

    A facile hydrothermal method was used to synthesize ZnMoO4:Er3+,Yb3+ nanoparticles. The shapes and sizes of the nanoparticles were well tuned by simply monitoring the pH of the starting solution. Microballs consisting of agglomerated nanograins were observed at strong acidic condition. At mild pH, plates and rectangular particles were realized, while strong basic pH stabilized rods. Further increasing pH to extremely basic conditions (pH > 13), rods changed to fragile hairy structures. The nucleation and growth mechanism of nanograins to form different morphology nanoparticles were studied and illustrated. XRD patterns confirmed well crystalline, triclinic structure despite small amount of aliovalent metal ions doping. Under 980 nm excitation, the ZnMoO4:Er3+,Yb3+ nanophosphor exhibited strong green (centered at 530 and 560 nm) and weak red (centered at 660 nm) upconversion (UC) emissions. Substitution of part of the Zn2+ ions by monovalent alkali ions intensified the UC emission intensities drastically. The order of intensification was K+>Na+>Li+>Rb+>no alkali ion. When Zn2+ ions were substituted with 10 at% K+ ions, the green and red UC emissions intensities increased by more than 50 and 15 folds, respectively. Time dependent measurements confirmed efficient Yb to Er energy transfer in the ZnMoO4:Er3+,Yb3+,K+ nanophosphor. The optimized ZnMoO4:Er3+,Yb3+,K+ phosphor exhibited intense UC emissions with 0.31% quantum yield. The upconverted light is visible to naked eye while pumping by laser of less than 1 mW power and opens door for variety of novel applications.

  18. First simultaneous detection of terrestrial ionospheric molecular ions in the Earth's inner magnetosphere and at the Moon

    NASA Astrophysics Data System (ADS)

    Dandouras, Iannis; Poppe, Andrew R.; Fillingim, Matt O.; Kistler, Lynn M.; Mouikis, Christopher G.; Rème, Henri

    2017-04-01

    Heavy molecular ions escaping from a planetary atmosphere can contribute to the long-term evolution of its composition. The ARTEMIS (Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun) spacecraft has recently observed outflowing molecular ions at lunar distances in the terrestrial magnetotail (Poppe et al., 2016). Backward particle tracing indicated that these ions should originate from the terrestrial inner magnetosphere. Here we have examined Cluster data acquired by the CIS-CODIF (Cluster Ion Spectrometry-Composition Distribution Function) ion mass spectrometer, obtained in the terrestrial magnetosphere. An event was selected where the orbital conditions were favourable and the Cluster spacecraft were in the high-latitude inner magnetosphere a few hours before the ARTEMIS molecular ion detection. Analysis shows that the CIS-CODIF instrument detected a series of energetic ion species, including not only O+ but also a group of molecular ions around 30 amu. Given the 5-7 m/Δm mass resolution of the instrument, these could include N2+, NO+, or O2+. These ions were detected by Cluster about 14 hours before the ARTEMIS observation in the lunar environment, a time which is compatible with the transfer to lunar distances. The event was during an active period followed by a northward rotation of the IMF. Although energetic heavy molecular ions have been detected in the storm time magnetosphere in the past (e.g. Klecker et al., 1986; Christon et al., 1994), this event constitutes the first coordinated observation in the Earth's inner magnetosphere and at the Moon. Additional events of coordinated outflowing molecular ion observations are currently under analysis. Future missions, as the proposed ESCAPE mission, should investigate in detail the mechanisms of molecular ion acceleration and escape, their link to the solar and magnetospheric activity, and their role in the magnetospheric dynamics and in the long-term evolution

  19. Is There Segregation of Rare Earth Ions in Garnet Optical Ceramics?

    NASA Astrophysics Data System (ADS)

    Boulon, Georges; Epicier, T.; Zhao, W.; Guzik, M.; Pan, Y.; Jiang, B.

    Research on advanced optical materials for a large variety of applications is always increasing. As an example, we can note high progress in solid-state laser sources like laser-diode (LD) - pumped solid-state lasers (DPSSL) including developments of new materials and high-power laser diode led to high-power and tuneable solid-state lasers. A wide variety of materials has been studied to develop more efficient and high power microchip lasers [1]. In end-pumping schemes, in particular, materials with a short absorption length for the LD pump beam are strongly anticipated for highly efficient operations because of the excellent match between the mode and pump beam profiles. High Nd3+ concentrations were so considered such as NdP5O14, LiNdP4O12 (LNP), and NdAl3(BO3)O4. However, crystal growths of these compositions are not so easy. Cubic crystals are much more researched. When looking at the literature for actual applications, we see immediately the importance of cubic garnet crystals for which dodecahedral (Y3+), octahedral (Al3+) and tetrahedral (Al3+) sites are considered as a reservoir for many activators like: Ce3+, Nd3+, Er3+, Tm3+, Ho3+, Yb3+ rare earth ions in dodecahedral symmetry sites and transition metal ions like Cr3+ in the octahedral symmetry sites or Cr4+ in the tetrahedral symmetry sites. Among garnet crystals, Y3Al5O12 (YAG) host is the most used, commercially produced by the Czochralski method. However, in the case of the most used Nd3+: YAG laser crystal, the Nd3+ concentration that affects the performance in laser applications, is strongly limited to 0.2-1.4 Nd3+ at. % as a result of the segregation distribution coefficient [1].

  20. In Situ Neutron Diffraction of Rare-Earth Phosphate Proton Conductors Sr/Ca-doped LaPO4 at Elevated Temperatures

    NASA Astrophysics Data System (ADS)

    Al-Wahish, Amal; Al-Binni, Usama; Bridges, C. A.; Huq, A.; Bi, Z.; Paranthaman, M. P.; Tang, S.; Kaiser, H.; Mandrus, D.

    Acceptor-doped lanthanum orthophosphates are potential candidate electrolytes for proton ceramic fuel cells. We combined neutron powder diffraction (NPD) at elevated temperatures up to 800° C , X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) to investigate the crystal structure, defect structure, thermal stability and surface topography. NPD shows an average bond length distortion in the hydrated samples. We employed Quasi-Elastic Neutron Scattering (QENS) and electrochemical impedance spectroscopy (EIS) to study the proton dynamics of the rare-earth phosphate proton conductors 4.2% Sr/Ca-doped LaPO4. We determined the bulk diffusion and the self-diffusion coefficients. Our results show that QENS and EIS are probing fundamentally different proton diffusion processes. Supported by the U.S. Department of Energy.

  1. [100] Directed Cu-doped h-CoO nanorods: elucidation of the growth mechanism and application to lithium-ion batteries.

    PubMed

    Nam, Ki Min; Choi, Young Cheol; Jung, Sung Chul; Kim, Yong-Il; Jo, Mi Ru; Park, Se Ho; Kang, Yong-Mook; Han, Young-Kyu; Park, Joon T

    2012-01-21

    Thermal decomposition of Co(acac)(3) and Cu(acac)(2) in benzylamine leads to the formation of [100] directed Cu-doped h-CoO nanorods, which are very stable in an aqueous solution. The formation mechanism of the [100] directed Cu-doped h-CoO nanorods is fully elucidated by using first-principles calculations, demonstrating that Cu-doping not only changes the growth direction but also enhances the stability of the nanorods significantly. Evaluation of the electrochemical performance of Cu-doped h-CoO nanorods shows high initial Coulombic efficiency and ultrahigh capacity with excellent cycling performance, indicating their suitability as an anode material for next generation lithium-ion batteries.

  2. A novel fluorescent probe (dtpa-bis(cytosine)) for detection of Eu(III) in rare earth metal ions.

    PubMed

    Yang, Fan; Ren, Peipei; Liu, Guanhong; Song, Youtao; Bu, Naishun; Wang, Jun

    2018-03-15

    In this paper, a novel fluorescent probe, dtpa-bis(cytosine), was designed and synthesized for detecting europium (Eu 3+ ) ion. Upon addition of Eu 3+ ions into the dtpa-bis(cytosine) solution, the fluorescence intensity can strongly be enhanced. Conversely, adding other rare earth metal ions, such as Y 3+ , Ce 3+ , Pr 3+ , Nd 3+ , Sm 3+ , Gd 3+ , Tb 3+ , Dy 3+ , Ho 3+ , Er 3+ , Yb 3+ and Lu 3+ , into dtpa-bis(cytosine) solution, the fluorescence intensity is decreased slightly. Some parameters affecting the fluorescence intensity of dtpa-bis(cytosine) solution in the presence of Eu 3+ ions were investigated, including solution pH value, Eu 3+ ion concentration and interfering substances. The detection mechanism of Eu 3+ ion using dtpa-bis(cytosine) as fluorescent probe was proposed. Under optimum conditions, the fluorescence emission intensities of Eu III -dtpa-bis(cytosine) at 375nm in the concentration range of 0.50×10 -5 mol∙L -1 -5.00×10 -5 mol∙L -1 of Eu 3+ ion display a better linear relationship. The limit of detection (LOD) was determined as 8.65×10 -7 mol∙L -1 and the corresponding correlation coefficient (R 2 ) of the linear equation is 0.9807. It is wished that the proposed method could be applied for sensitively and selectively detecting Eu 3+ ion. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. A novel fluorescent probe (dtpa-bis(cytosine)) for detection of Eu(III) in rare earth metal ions

    NASA Astrophysics Data System (ADS)

    Yang, Fan; Ren, Peipei; Liu, Guanhong; Song, Youtao; Bu, Naishun; Wang, Jun

    2018-03-01

    In this paper, a novel fluorescent probe, dtpa-bis(cytosine), was designed and synthesized for detecting europium (Eu3 +) ion. Upon addition of Eu3 + ions into the dtpa-bis(cytosine) solution, the fluorescence intensity can strongly be enhanced. Conversely, adding other rare earth metal ions, such as Y3 +, Ce3 +, Pr3 +, Nd3 +, Sm3 +, Gd3 +, Tb3 +, Dy3 +, Ho3 +, Er3 +, Yb3 + and Lu3 +, into dtpa-bis(cytosine) solution, the fluorescence intensity is decreased slightly. Some parameters affecting the fluorescence intensity of dtpa-bis(cytosine) solution in the presence of Eu3 + ions were investigated, including solution pH value, Eu3 + ion concentration and interfering substances. The detection mechanism of Eu3 + ion using dtpa-bis(cytosine) as fluorescent probe was proposed. Under optimum conditions, the fluorescence emission intensities of EuIII-dtpa-bis(cytosine) at 375 nm in the concentration range of 0.50 × 10- 5 mol • L- 1-5.00 × 10- 5 mol • L- 1 of Eu3 + ion display a better linear relationship. The limit of detection (LOD) was determined as 8.65 × 10- 7 mol • L- 1 and the corresponding correlation coefficient (R2) of the linear equation is 0.9807. It is wished that the proposed method could be applied for sensitively and selectively detecting Eu3 + ion.

  4. The effect of 0.025 Al-doped in Li4Ti5O12 material on the performance of half cell lithium ion battery

    NASA Astrophysics Data System (ADS)

    Priyono, Slamet; Triwibowo, Joko; Prihandoko, Bambang

    2016-02-01

    The effect of 0.025 Al-doped Li4Ti5O12 as anode material for Lithium Ion battery had been studied. The pure and 0.025 Al-doped Li4Ti5O12 were synthesized through solid state process in air atmosphere. Physical characteristics of all samples were observed by XRD, FTIR, and PSA. The XRD analysis revealed that the obtained particle was highly crystalline and had a face-centered cubic spinel structure. The XRD pattern also showed that the 0.025 Al-doped on the Li4Ti5O12 did not change crystal structure of Li4Ti5O12. FTIR analysis confirmed that the spinel structure in fingerprint region was unchanged when the structure was doped by 0.025 Al. However the doping of 0.025 Al increased particle size significantly. The electrochemical performance was studied by using cyclic voltammetry (CV) and charge-discharge (CD) curves. Electrochemical analysis showed that pure Li4Ti5O12 has higher capacity than 0.025 Al-doped Li4Ti5O12 had. But 0.025 Al-doped Li4Ti5O12 possesses a better cycling stability than pure Li4Ti5O12.

  5. The reduction of critical H implantation dose for ion cut by incorporating B-doped SiGe/Si superlattice into Si substrate

    NASA Astrophysics Data System (ADS)

    Xue, Zhongying; Chen, Da; Jia, Pengfei; Wei, Xing; Di, Zengfeng; Zhang, Miao

    2016-11-01

    An approach to achieve Si or SiGe film exfoliation with as low as 3 × 1016/cm2 H implantation dose was investigated. Two intrinsic Si0.75Ge0.25/Si samples, merged with B-doped Si0.75Ge0.25 layer and B-doped Si0.75Ge0.25/Si superlattice (SL) layer respectively, were used to study the formation of crack after 3 × 1016/cm2 H implantation and annealing. For the sample into which B doped Si0.75Ge0.25 layer is incorporated, only few discrete cracks are observed along both sides of the B doped Si0.75Ge0.25 layer; on the contrary, a continuous (100) oriented crack is formed in the B-doped Si0.75Ge0.25/Si SL layer, which means ion cut can be achieved using this material with 3 × 1016/cm2 H implantation. As the SIMS profiles confirm that hydrogen tends to be trapped at B-doped SiGe/Si interface, the formation of continuous crack in SL layer can be ascribed to the more efficient hydrogen trapping by the multiple B-doped SiGe/Si interfaces.

  6. L-lactic acid and sodium p-toluenesulfonate co-doped polypyrrole for high performance cathode in sodium ion battery

    NASA Astrophysics Data System (ADS)

    Liao, Qishu; Hou, Hongying; Liu, Xianxi; Yao, Yuan; Dai, Zhipeng; Yu, Chengyi; Li, Dongdong

    2018-04-01

    In this work, polypyrrole (PPy) was co-doped with L-lactic acid (LA) and sodium p-toluenesulfonate (TsONa) for high performance cathode in sodium ion battery (SIB) via facile one-step electropolymerization on Fe foil. The as-synthesized LA/TsONa co-doped PPy cathode was investigated in terms of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), galvanostatic charge/discharge and cyclic voltammetry (CV). The results suggested that some oval-bud-like LA/TsONa co-doped PPy particles did form and tightly combine with the surface of Fe foil; furthermore, LA/TsONa co-doped PPy cathode also delivered higher electrochemical performances than TsONa mono-doped PPy cathode. For example, the initial specific discharge capacity was as high as about 124 mAh/g, and the reversible specific capacity still maintained at about 110 mAh/g even after 50 cycles, higher than those of TsONa mono-doped PPy cathode. The synergy effect of multi components of LA/TsONa co-doped PPy cathode should be responsible for high electrochemical performances.

  7. Enrichment of rare earth metal ions by the highly selective adsorption of phytate intercalated layered double hydroxide.

    PubMed

    Jin, Cheng; Liu, Huimin; Kong, Xianggui; Yan, Hong; Lei, Xiaodong

    2018-02-27

    Phytate intercalated MgAl layered double hydroxide (MgAl-LDH) was prepared by an anion exchange method with the precursor NO 3 - containing MgAl-LDH. The final as-synthesized product [Mg 0.69 Al 0.31 (OH) 2 ] (phytateNa 6 ) 0.05 (NO 3 ) 0.01 ·mH 2 O (phytate-LDH) has highly selective adsorption ability for some metal ions and can be used to enrich rare earth metal ions in mixed solution, such as Pr 3+ and Ce 3+ from a mixed solution of them with Pb 2+ and Co 2+ . At first, phytate-LDH has good adsorption performance for these ions in single metal ion solutions. At low concentration (below 10 mg L -1 ), all the capture rates of the four metal ions were more than 97%, for highly toxic Pb 2+ it was even up to nearly 100%, and a high capture rate (99.87%) was maintained for Pb 2+ at a high concentration (100 mg L -1 ). When all the four metal ions are co-existing in aqueous solution, the selectivity order is Pb 2+ ≫ Pr 3+ ≈ Ce 3+ > Co 2+ . In a solution containing mixtures of the three metal ions of Pr 3+ , Ce 3+ , and Co 2+ , the selectivity order is Pr 3+ ≈ Ce 3+ ≫ Co 2+ , and in a solution containing mixtures of Pr 3+ with Co 2+ and Ce 3+ with Co 2+ , the selectivity orders are Pr 3+ ≫ Co 2+ and Ce 3+ ≫ Co 2+ , respectively. The high selectivity and adsorption capacities for Pb 2+ , Co 2+ , Pr 3+ , and Ce 3+ result in the efficient removal of Pb 2+ and enrichment of the rare earth metal ions Pr 3+ and Ce 3+ by phytate-LDH. Based on the elemental analysis, it is found that the difference of the adsorption capacities is mainly due to the different coordination number of them with phytate-LDH. With molecular simulation, we believe that the adsorption selectivity is due to the difference of the binding energy between the metal ion and phytate-LDH. Therefore, the phytate-LDH is promising for the enrichment and/or purification of the rare earth metal ions and removal of toxic metal ions from waste water.

  8. Effects of Zirconium Ions Doping on the Structural and Thermochromic Properties of VO2 Thin Films

    NASA Astrophysics Data System (ADS)

    Li, Yuanbao; Liu, Juncheng; Wang, Danping; Dang, Yuanyuan

    2017-11-01

    As an inorganic functional material, VO2 thin films are expected to be used for smart windows. However, these films are not conducive to practical applications when the phase transition temperature ( Tc) of the VO2 is approximately 68°C, which is greater than room temperature. To decrease Tc, the effect of Zr4+ doping on the structure and properties of VO2 films were investigated. The films were prepared using a sol-gel process, spin-coating on quartz glasses, and annealing at 525°C in a tube furnace within a nitrogen atmosphere. The results demonstrate that these films have a highly preferential crystalline orientation on the substrate; however, the primary two x-ray diffraction pattern peaks shift slightly toward the small angle, and when 7 at.% Zr4+ was doped in the VO2 film, the deviation angle was 0.16°, and the crystallite size was approximately 98 nm. A large number of grains were found on the surface of the pure VO2 films, but all the Zr4+ doped films had a layered structure, and the thickness of the films was approximately 200 nm. The Tc of these films was characterized using differential scanning calorimetry, and the luminous and solar transmittance was characterized using a UV-Vis-NIR spectrophotometer, which demonstrated that the effect of Zr4+ doping decreased Tc by approximately 1°C per 1 at.% on average, and the Tc of the 7 at.% film was slightly greater than that of the 5 at.% film, the phase transition temperature of which was 61.4°C. The transmittance decreased as the doping concentration increased, and 1 at.% Zr4+ doping increased the luminous regulation efficiency (Δ T lum) and solar modulation efficiency (Δ T sol). The Δ T lum of the pure VO2 film and the 1 at.% Zr4+-doped VO2 films was 10.9% and 11.2%, and Δ T sol was 14.4 and 15.2%, respectively.

  9. Efficient 2 μm emission and energy transfer mechanism of Ho3+ doped fluorophosphate glass sensitized by Er3+ ions

    NASA Astrophysics Data System (ADS)

    Gao, Xinyu; Tian, Ying; Liu, Qunhuo; Yang, Shuai; Jing, Xufeng; Zhang, Junjie; Xu, Shiqing

    2018-06-01

    Fluorophosphate glass co-doped with Er3+ and Ho3+ ions has been synthesized by high temperature melting method. Using a commercially available 980 nm laser diode, intense about 2 μm emissions were successfully obtained in present Ho3+/Er3+ co-doped glasses without obvious quenching. To understand 2 μm fluorescence behaviors of the prepared glasses, 1.55 μm emission spectra, energy transfer mechanism and microparameters from different levels of Er3+ to Ho3+ ions have been obtained and discussed. As a result, the Er3+/Ho3+ co-doped fluorophosphate glass with excellent spectroscopic properties might be appropriate host material for 2 μm solid laser.

  10. The adsorption kinetics of metal ions onto different microalgae and siliceous earth.

    PubMed

    Schmitt, D; Müller, A; Csögör, Z; Frimmel, F H; Posten, C

    2001-03-01

    In the present work the adsorption kinetics of the six metal ions aluminum, zinc, mercury, lead, copper, and cadmium onto living microalgae were measured. The freshwater green microalga Scenedesmus subspicatus, the brackish water diatom Cyclotella cryptica, the seawater diatom Phaeodactylum tricornutum, and the seawater red alga Porphyridium purpureum were the subject of investigation. In most cases the adsorption rate of the metals could be well described by using the equation of the Langmuir adsorption rate expression. Inverse parameter estimation allowed the determination of the rate constants of the adsorption process and the maximum metal content of the algae. The highest values for the rate constant were obtained for Porphyridium purpureum followed by Phaeodactylum tricornutum. High values for the maximum content were obtained for Cyclotella cryptica and Scenedesmus subspicatus. The maximum rate constant was 24.21 h-1 for the adsorption of Hg to Porphyridium purpureum whereas the maximum metal content (0.243 g g-1) was obtained for Zn on Cyclotella cryptica. A comparison of these values with those obtained for the mineral siliceous earth exhibiting low maximum content and high adsorption rates reveals that the mechanism of adsorption onto the algae is a mixture of adsorption and accumulation.

  11. Non-resonant excitation of rare-earth ions via virtual Auger process

    NASA Astrophysics Data System (ADS)

    Yassievich, I. N.

    2011-05-01

    The luminescence of rare-earth ions (REI) is often intensified by defects associated with REIs or excitons bound to these defects. In this paper we show that the presence of such a state opens the possibility of non-resonance optical pumping via the process involving virtual Auger transition. It is the second order perturbation process when an electron arrives in an virtual intermediate state due to the optical transition (the first step) and the Auger transition is the second one. We have calculated the cross-section of such an excitation process when the optical transition is accompanied by creation of the exciton bound to the defect associated with REI and obtained a simple analytical expression for the cross-section. The excess energy of the excitation quanta is taken away by multiphonon emission. The electron-phonon interaction with local phonon vibrations of the bound exciton is assumed to determine the multiphonon process. It is shown that the probability of the process under study exceeds considerably the probability of direct optical 4f-4f absorption even in the case when the energy distance between the excitation quantum energy and the exciton energy is about 0.1 of the exciton energy. The excitation mechanism considered leads to the appearance of a broad unsymmetrical band in the excitation spectrum with the red side much wider and flatter than the blue one.

  12. Synthesis and characterization of three-dimensional transition metal ions doped zinc oxide based dilute magnetic semiconductor thin films

    NASA Astrophysics Data System (ADS)

    Samanta, Kousik

    Dilute magnetic semiconductors (DMS), especially 3d-transition metal (TM) doped ZnO based DMS materials are the most promising candidates for optoelectronics and spintronics applications; e.g. in spin light emitting diode (SLED), spin transistors, and spin field effect transistors (SFET), etc. In the present dissertation, thin films of Zn1-xTMxO (TM = Co2+, Cu2+, and Mn2+) were grown on (0001) oriented Al2O3 substrates by pulsed laser deposition (PLD) technique. The films were highly c-axis oriented, nearly single crystalline, and defects free for a limited concentration of the dilution of transition metal ions. In particular, we have obtained single crystalline phases of Zn1-xTMxO thin films for up to 10, 3, and 5 stoichiometric percentages of Co2+, Cu2+, and Mn2+ respectively. Raman micro-probe system was used to understand the structural and lattice dynamical properties at different physical conditions. The confinement of optical phonons in the disorder lattice was explained by alloy potential fluctuation (APF) using a spatial correlation (SC) model. The detailed analysis of the optical phonon behavior in disorder lattice confirmed the substitution of the transition metal ions in Zn 2+ site of the ZnO host lattice. The secondary phases of ZnCo 2O4, CuO, and ZnMn2O4 were detected in higher Co, Cu, and Mn doped ZnO thin films respectively; where as, XRD did not detect these secondary phases in the same samples. Room temperature ferromagnetism was observed in Co2+ and Cu2+ ions doped ZnO thin films with maximum saturation magnetization (Ms) of 1.0 and 0.76 muB respectively. The origin of the observed ferromagnetism in Zn1-xCoxO thin films was tested by the controlled introduction of shallow donors (Al) in Zn0.9-x Co0.1O:Alx (x = 0.005 and 0.01) thin films. The saturation magnetization for the 10% Co-doped ZnO (1.0 muB /Co) at 300K reduced (˜0.25 muB/Co) due to Al doping. The observed ferromagnetism and the reduction due to Al doping can be explained by the Bound

  13. Energies of rare-earth ion states relative to host bands in optical materials from electron photoemission spectroscopy

    NASA Astrophysics Data System (ADS)

    Thiel, Charles Warren

    There are a vast number of applications for rare-earth-activated materials and much of today's cutting-edge optical technology and emerging innovations are enabled by their unique properties. In many of these applications, interactions between the rare-earth ion and the host material's electronic states can enhance or inhibit performance and provide mechanisms for manipulating the optical properties. Continued advances in these technologies require knowledge of the relative energies of rare-earth and crystal band states so that properties of available materials may be fully understood and new materials may be logically developed. Conventional and resonant electron photoemission techniques were used to measure 4f electron and valence band binding energies in important optical materials, including YAG, YAlO3, and LiYF4. The photoemission spectra were theoretically modeled and analyzed to accurately determine relative energies. By combining these energies with ultraviolet spectroscopy, binding energies of excited 4fN-15d and 4fN+1 states were determined. While the 4fN ground-state energies vary considerably between different trivalent ions and lie near or below the top of the valence band in optical materials, the lowest 4f N-15d states have similar energies and are near the bottom of the conduction band. As an example for YAG, the Tb3+ 4f N ground state is in the band gap at 0.7 eV above the valence band while the Lu3+ ground state is 4.7 eV below the valence band maximum; however, the lowest 4fN-15d states are 2.2 eV below the conduction band for both ions. We found that a simple model accurately describes the binding energies of the 4fN, 4fN-1 5d, and 4fN+1 states. The model's success across the entire rare-earth series indicates that measurements on two different ions in a host are sufficient to predict the energies of all rare-earth ions in that host. This information provides new insight into electron transfer transitions, luminescence quenching, and valence

  14. Incorporation of heterostructured Sn/SnO nanoparticles in crumpled nitrogen-doped graphene nanosheets for application as anodes in lithium-ion batteries.

    PubMed

    Du, Fei-Hu; Liu, Yu-Si; Long, Jie; Zhu, Qian-Cheng; Wang, Kai-Xue; Wei, Xiao; Chen, Jie-Sheng

    2014-09-07

    Sn/SnO nanoparticles are incorporated in crumpled nitrogen-doped graphene nanosheets by a simple melting diffusion method. The resulting composite exhibits large specific capacity, excellent cycling stability and high rate capability as an anode for lithium-ion batteries.

  15. In situ electro-polymerization of nitrogen doped carbon dots and their application in an electrochemiluminescence biosensor for the detection of intracellular lead ions.

    PubMed

    Xiong, Chengyi; Liang, Wenbin; Wang, Haijun; Zheng, Yingning; Zhuo, Ying; Chai, Yaqin; Yuan, Ruo

    2016-04-25

    Here, a novel sensitive electrochemiluminescence (ECL) biosensor using N doped carbon dots (N-CDs) in situ electro-polymerized onto a glassy carbon electrode (GCE) as luminophores, and Pd-Au hexoctahedrons (Pd@Au HOHs) as enhancers, was developed for the detection of intracellular lead ions (Pb(2+)).

  16. Enhancement of pump absorption efficiency by bending and twisting of double clad rare earth doped fibers (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Koška, Pavel; Peterka, Pavel; Doya, Valérie; Aubrecht, Jan; Kasik, Ivan; Podrazký, Ondřej

    2017-05-01

    chaotic double-clad fiber amplifier," Opt. Lett., vol. 26, no. 12, pp. 872-874, (2001). [2] Kouznetsov, D., Moloney, J. V., "Efficiency of pump absorption in double-clad fiber amplifiers. II. Broken circular symmetry," J. Opt. Soc. Am. B, vol. 19, no. 6, pp. 1259-1263, June 2002. [3] Li, Y., Jackson, S. D., Fleming, S., "High absorption and low splice loss properties of hexagonal double-clad fiber," IEEE Photonics Technol. Lett., vol 16, no. 11, pp. 2502-2504, Nov. 2004. [4] Ko\\vska, P. and Peterka, P., "Numerical analysis of pump propagation and absorption in specially tailored double-clad rare-earth doped fiber," Optical and Quantum Electronics, vol. 47, no. 9, pp. 3181-3191 (2015). [5] Ko\\vska, P., Peterka, P., and Doya, V., "Numerical modeling of pump absorption in coiled and twisted double-clad fibers," IEEE J. Sel. Top. Quantum Electron., vol. 22, no. 2 (2016). [6] Ko\\vska, P., Peterka, P., Aubrecht, J., Podrazký, O., Todorov, F., Becker, M., Baravets, Y., Honzátko, P., and Kašík, I., "Enhanced pump absorption efficiency in coiled and twisted double-clad thulium-doped fibers," Opt. Express, vol. 24, no. 1, pp. 102-107 (2016).

  17. Synthesis and the luminescent properties of the Nd3+ ions doped three kinds of fluoride nanocrystals in organic solvents

    NASA Astrophysics Data System (ADS)

    Chen, Zhuo; Tian, Changyong; Bo, Shuhui; Liu, Xinhou; Zhen, Zhen

    2015-10-01

    Oleic acid (OA)-modified LaF3:Nd, NaYF4:Nd and CaF2:Nd nanocrystals (NCs) with the different Nd3+ ion concentration (2% and 5%) have been prepared. The structure and morphology of NCs were identified by XRD, TEM, FT-IR and TGA. The size of OA-modified NC is a mean diameter of 5-10 nm and can be dispersed in common organic solvents to form a transparent solution. The optical loss of NCs in organic solvent is the first time to discuss in this work. The luminescence properties of NCs were also characterized and studied by fluorescence spectrometer. The nanoparticles in solid and in the solution all exhibited the strong emission at the 1060 nm when the materials were excited around 800 nm. Compared with the LaF3 and CaF2 matrix, NaYF4 as the host can protect the Nd3+ ions more efficiently away from the nonradiative transitions. The longest luminescent lifetime of the solid NaYF4:2%Nd NCs was up to 136 μs, and the little difference of the fluorescence lifetime existed between the NCs in solid state and in solution. The low optical loss in organic solvent indicated that the Nd3+ ions-doped fluoride NCs are promising materials for optical amplification fields.

  18. Y-doped Li 8ZrO 6: A Li-Ion Battery Cathode Material with High Capacity

    DOE PAGES

    Huang, Shuping; Wilson, Benjamin E.; Wang, Bo; ...

    2015-08-11

    We study—experimentally and theoretically—the energetics, structural changes, and charge flows during the charging and discharging processes for a new high-capacity cathode material, Li 8ZrO 6 (LZO), which we study both pure and yttrium-doped. We quantum mechanically calculated the stable delithiated configurations, the delithiation energy, the charge flow during delithiation, and the stability of the delithiated materials. We find that Li atoms are easier to extract from tetrahedral sites than octahedral ones. We calculate a large average voltage of 4.04 eV vs Li/Li + for delithiation of the first Li atom in a primitive cell, which is confirmed by galvanostatic charge/dischargemore » cycling data. Energy calculations indicate that topotactic delithiation is kinetically favored over decomposition into Li, ZrO 2, and O 2 during the charging process, although the thermodynamic energy of the topotactic reaction is less favorable. When one or two lithium atoms are extracted from a primitive cell of LZO, its volume and structure change little, whereas extraction of the third lithium greatly distorts the layered structure. The Li 6ZrO 6 and Li 5ZrO 6 delithiation products can be thermodynamically metastable to release of O 2. Experimentally, materials with sufficiently small particle size for efficient delithiation and relithiation were achieved within an yttrium-doped LZO/carbon composite cathode that exhibited an initial discharge capacity of at least 200 mAh/g over the first 10 cycles, with 142 mAh/g maintained after 60 cycles. Computations predict that during the charging process, the oxygen ion near the Li vacancy is oxidized for both pure LZO and yttrium-doped LZO, which leads to a small-polaron hole.« less

  19. Y-doped Li 8ZrO 6: A Li-Ion Battery Cathode Material with High Capacity

    SciT

    Huang, Shuping; Wilson, Benjamin E.; Wang, Bo

    We study—experimentally and theoretically—the energetics, structural changes, and charge flows during the charging and discharging processes for a new high-capacity cathode material, Li 8ZrO 6 (LZO), which we study both pure and yttrium-doped. We quantum mechanically calculated the stable delithiated configurations, the delithiation energy, the charge flow during delithiation, and the stability of the delithiated materials. We find that Li atoms are easier to extract from tetrahedral sites than octahedral ones. We calculate a large average voltage of 4.04 eV vs Li/Li + for delithiation of the first Li atom in a primitive cell, which is confirmed by galvanostatic charge/dischargemore » cycling data. Energy calculations indicate that topotactic delithiation is kinetically favored over decomposition into Li, ZrO 2, and O 2 during the charging process, although the thermodynamic energy of the topotactic reaction is less favorable. When one or two lithium atoms are extracted from a primitive cell of LZO, its volume and structure change little, whereas extraction of the third lithium greatly distorts the layered structure. The Li 6ZrO 6 and Li 5ZrO 6 delithiation products can be thermodynamically metastable to release of O 2. Experimentally, materials with sufficiently small particle size for efficient delithiation and relithiation were achieved within an yttrium-doped LZO/carbon composite cathode that exhibited an initial discharge capacity of at least 200 mAh/g over the first 10 cycles, with 142 mAh/g maintained after 60 cycles. Computations predict that during the charging process, the oxygen ion near the Li vacancy is oxidized for both pure LZO and yttrium-doped LZO, which leads to a small-polaron hole.« less

  20. Employing Synergetic Effect of Doping and Thin Film Coating to Boost the Performance of Lithium-Ion Battery Cathode Particles

    PubMed Central

    Patel, Rajankumar L.; Jiang, Ying-Bing; Choudhury, Amitava; Liang, Xinhua

    2016-01-01

    Atomic layer deposition (ALD) has evolved as an important technique to coat conformal protective thin films on cathode and anode particles of lithium ion batteries to enhance their electrochemical performance. Coating a conformal, conductive and optimal ultrathin film on cathode particles has significantly increased the capacity retention and cycle life as demonstrated in our previous work. In this work, we have unearthed the synergetic effect of electrochemically active iron oxide films coating and partial doping of iron on LiMn1.5Ni0.5O4 (LMNO) particles. The ionic Fe penetrates into the lattice structure of LMNO during the ALD process. After the structural defects were saturated, the iron started participating in formation of ultrathin oxide films on LMNO particle surface. Owing to the conductive nature of iron oxide films, with an optimal film thickness of ~0.6 nm, the initial capacity improved by ~25% at room temperature and by ~26% at an elevated temperature of 55 °C at a 1C cycling rate. The synergy of doping of LMNO with iron combined with the conductive and protective nature of the optimal iron oxide film led to a high capacity retention (~93% at room temperature and ~91% at 55 °C) even after 1,000 cycles at a 1C cycling rate. PMID:27142704

  1. Terbium Ion Doping in Ca3Co4O9: A Step towards High-Performance Thermoelectric Materials

    PubMed Central

    Saini, Shrikant; Yaddanapudi, Haritha Sree; Tian, Kun; Yin, Yinong; Magginetti, David; Tiwari, Ashutosh

    2017-01-01

    The potential of thermoelectric materials to generate electricity from the waste heat can play a key role in achieving a global sustainable energy future. In order to proceed in this direction, it is essential to have thermoelectric materials that are environmentally friendly and exhibit high figure of merit, ZT. Oxide thermoelectric materials are considered ideal for such applications. High thermoelectric performance has been reported in single crystals of Ca3Co4O9. However, for large scale applications single crystals are not suitable and it is essential to develop high-performance polycrystalline thermoelectric materials. In polycrystalline form, Ca3Co4O9 is known to exhibit much weaker thermoelectric response than in single crystal form. Here, we report the observation of enhanced thermoelectric response in polycrystalline Ca3Co4O9 on doping Tb ions in the material. Polycrystalline Ca3−xTbxCo4O9 (x = 0.0–0.7) samples were prepared by a solid-state reaction technique. Samples were thoroughly characterized using several state of the art techniques including XRD, TEM, SEM and XPS. Temperature dependent Seebeck coefficient, electrical resistivity and thermal conductivity measurements were performed. A record ZT of 0.74 at 800 K was observed for Tb doped Ca3Co4O9 which is the highest value observed till date in any polycrystalline sample of this system. PMID:28317853

  2. Enhanced Scattering of Diffuse Ions on Front of the Earth's Quasi-Parallel Bow Shock: a Case Study

    NASA Astrophysics Data System (ADS)

    Kis, A.; Matsukiyo, S.; Otsuka, F.; Hada, T.; Lemperger, I.; Dandouras, I. S.; Barta, V.; Facsko, G. I.

    2017-12-01

    In the analysis we present a case study of three energetic upstream ion events at the Earth's quasi-parallel bow shock based on multi-spacecraft data recorded by Cluster. The CIS-HIA instrument onboard Cluster provides partial energetic ion densities in 4 energy channels between 10 and 32 keV.The difference of the partial ion densities recorded by the individual spacecraft at various distances from the bow shock surface makes possible the determination of the spatial gradient of energetic ions.Using the gradient values we determined the spatial profile of the energetic ion partial densities as a function of distance from the bow shock and we calculated the e-folding distance and the diffusion coefficient for each event and each ion energy range. Results show that in two cases the scattering of diffuse ions takes place in a normal way, as "by the book", and the e-folding distance and diffusion coefficient values are comparable with previous results. On the other hand, in the third case the e-folding distance and the diffusion coefficient values are significantly lower, which suggests that in this case the scattering process -and therefore the diffusive shock acceleration (DSA) mechanism also- is much more efficient. Our analysis provides an explanation for this "enhanced" scattering process recorded in the third case.

  3. Formation of the high-energy ion population in the earth's magnetotail: spacecraft observations and theoretical models

    NASA Astrophysics Data System (ADS)

    Artemyev, A. V.; Vasko, I. Y.; Lutsenko, V. N.; Petrukovich, A. A.

    2014-10-01

    We investigate the formation of the high-energy (E ∈ [20,600] keV) ion population in the earth's magnetotail. We collect statistics of 4 years of Interball / Tail observations (1995-1998) in the vicinity of the neutral plane in the magnetotail region (X <-17 RE, |Y| ≤ 20 RE in geocentric solar magnetospheric (GSM) system). We study the dependence of high-energy ion spectra on the thermal-plasma parameters (the temperature Ti and the amplitude of bulk velocity vi) and on the magnetic-field component Bz. The ion population in the energy range E ∈ [20,600] keV can be separated in the thermal core and the power-law tail with the slope (index) ~ -4.5. Fluxes of the high-energy ion population increase with the growth of Bz, vi and especially Ti, but spectrum index seems to be independent on these parameters. We have suggested that the high-energy ion population is generated by small scale transient processes, rather than by the global reconfiguration of the magnetotail. We have proposed the relatively simple and general model of ion acceleration by transient bursts of the electric field. This model describes the power-law energy spectra and predicts typical energies of accelerated ions.

  4. Iron doped LiCoPO4 thin films for lithium-ion microbatteries obtained by ns pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Smaldone, A.; Brutti, S.; De Bonis, A.; Ciarfaglia, N.; Santagata, A.; Teghil, R.

    2018-07-01

    Well crystallized and homogeneous iron doped LiCoPO4 (LCfP) thin films have been grown by ns Pulsed Laser Ablation, at ambient temperature without any substrate heating or post-annealing treatments. The films have been deposited in vacuum and in the presence of buffer gases (O2, Ar) and it has been found that their crystallinity, structure and morphology depend on pressure conditions. The films have been studied by Scanning Electron Microscopy and X Ray Diffraction, while their first steps of growth have been characterized by Transmission Electron Microscopy. A study of the plasma produced by the laser ablation in the different pressure conditions has been carried out with the aim of elucidate the mechanisms involved in the films deposition. LCfP thin films have been also tested as microelectrodes in lithium cells in galvanostatic condition for analyzing the reversibility of the lithium-ion battery.

  5. A Room Temperature Nitric Oxide Gas Sensor Based on a Copper-Ion-Doped Polyaniline/Tungsten Oxide Nanocomposite

    PubMed Central

    Wang, Shih-Han; Shen, Chi-Yen; Su, Jian-Ming; Chang, Shiang-Wen

    2015-01-01

    The parts-per-billion-level nitric oxide (NO) gas sensing capability of a copper-ion-doped polyaniline/tungsten oxide nanocomposite (Cu2+/PANI/WO3) film coated on a Rayleigh surface acoustic wave device was investigated. The sensor developed in this study was sensitive to NO gas at room temperature in dry nitrogen. The surface morphology, dopant distribution, and electric properties were characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy mapping, and Hall effect measurements, respectively. The Cu2+/PANI/WO3 film exhibited high NO gas sensitivity and selectivity as well as long-term stability. At 1 ppb of NO, a signal with a frequency shift of 4.3 ppm and a signal-to-noise ratio of 17 was observed. The sensor exhibited distinct selectivity toward NO gas with no substantial response to O2, NH3 and CO2 gases. PMID:25811223

  6. Super-resolution nanofabrication with metal-ion doped hybrid material through an optical dual-beam approach

    SciT

    Cao, Yaoyu; Li, Xiangping; Gu, Min, E-mail: mgu@swin.edu.au

    2014-12-29

    We apply an optical dual-beam approach to a metal-ion doped hybrid material to achieve nanofeatures beyond the optical diffraction limit. By spatially inhibiting the photoreduction and the photopolymerization, we realize a nano-line, consisting of polymer matrix and in-situ generated gold nanoparticles, with a lateral size of sub 100 nm, corresponding to a factor of 7 improvement compared to the diffraction limit. With the existence of gold nanoparticles, a plasmon enhanced super-resolution fabrication mechanism in the hybrid material is observed, which benefits in a further reduction in size of the fabricated feature. The demonstrated nanofeature in hybrid materials paves the way formore » realizing functional nanostructures.« less

  7. Nitrogen-doped carbon coated MnO nanopeapods as superior anode materials for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Ding, Yu; Chen, Lihui; Pan, Pei; Du, Jun; Fu, Zhengbing; Qin, Caiqin; Wang, Feng

    2017-11-01

    High performance nitrogen-doped carbon (NC) materials decorated with MnO hybrid (MnO@NC) composites with a nanopeapod appearance were synthesized by with a simple hydrothermal method and insuit-polymeric route. As an anode material for lithium ion batteries (LIBs), the nanopeapod structure of MnO@NC composites with internal void spaces exhibits good rate capability, high conductivity and excellent cycling stability. After 200 cycles, the nanopeapod composites yield a specific capacity of 775.4 mAh g-1 at 100 mA g-1 and a high-rate capacity of 559.7 mAh g-1 at 1000 mA g-1. The proposed synthesis of nanopeapod structure composites with an internal room is an efficient design with excellent electrode materials for rechargeable LIBs.

  8. Growth and spectral-luminescent study of SrMoO4 crystals doped with Tm3+ ions

    NASA Astrophysics Data System (ADS)

    Dunaeva, E. E.; Zverev, P. G.; Doroshenko, M. E.; Nekhoroshikh, A. V.; Ivleva, L. I.; Osiko, V. V.

    2016-03-01

    SrMoO4 crystals doped with Tm3+ ions have been produced from a melt using the Czochralski method; their spectral-luminescent characteristics have been studied, and laser radiation has been generated at the wavelength of 1.94 μm using laser-diode excitation. The high absorption section at the wavelength of 795 nm, the fairly high luminescence section, the long lifetime at the upper laser level 3F4 of 1.5 ms, and a wide luminescence band allow one to hope for developing efficient tunable Tm3+: SrMoO4 crystal lasers with diode pumping in the range of 1.7-2.0 μm, which are capable of implementing SRS self-transformation of radiation into the middle IR band.

  9. X-Ray Absorption Spectroscopy Studies of the Atomic Structure of Zirconium-Doped Lithium Silicate Glasses and Glass-Ceramics, Zirconium-Doped Lithium Borate Glasses, and Vitreous Rare-Earth Phosphates

    NASA Astrophysics Data System (ADS)

    Yoo, Changhyeon

    In the first part of this work, the atomic-scale structure around rare-earth (RE = Pr, Nd, Eu, Dy, and Er) cations (RE3+) in rare-earth sodium ultraphosphate (REUP) glasses were investigated using RE LIII -edge (RE = Nd, Er, Dy, and Eu) and K-edge (RE = Pr and Dy) Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy. (RE2O 3)x(Na2O)y(P2O5) 1-x-y glasses in the compositional range 0 ≤ x ≤ 0.14 and 0.3 ≤ x + y ≤ 0.4 were studied. For the nearest oxygen shell, the RE-oxygen (RE-O) coordination number decreases from 10.8 to 6.5 with increasing RE content for Pr-, Nd-, Dy-, and Er-doped sodium ultraphosphate glasses. For Eu-doped samples, the Eu-O coordination number was between 7.5 and 8.8. Also, the RE-O mean distance ranges were between 2.43-2.45 A, 2.40-2.43 A, 2.36-2.38 A, 2.30-2.35 A, and 2.28-2.30 A for Pr-, Nd-, Eu-, Dy-, and Er-doped samples, respectively. In the second part, a series of Zr-doped (3-10 mol%) lithium silicate (ZRLS) glass-ceramics and their parent glasses and a series of Zr-doped (2-6 mol% ZrO2) lithium borate (ZRLB) glasses were investigated using Zr K-edge EXAFS and X-ray Absorption Near Edge Structure (XANES) spectroscopy. Immediate coordination environments of all ZRLS glasses are remarkably similar for different compositions. For the nearest oxygen shell, the Zr-O coordination number ranges were between 6.1 and 6.3 for nucleated and crystallized samples, respectively. Also, the Zr-O mean distance remains similar around 2.10 A. For these glasses, the composition dependence of structural parameters was small. Small changes in the coordination environment were observed for ZRLS glass-ceramics after thermal treatments. In contrast, Zr coordination environment in ZRLB glasses appear to depend appreciably on the Zr concentration. For the nearest oxygen shell, the Zr-O coordination number increased from 6.1 to 6.8 and the Zr-O distance decreased from 2.18 A to 2.14 A with decreasing ZrO2 content.

  10. Computational Studies of Thermodynamics and Kinetics of Metal Oxides in Li-Ion Batteries and Earth's Lower Mantle Materials

    NASA Astrophysics Data System (ADS)

    Xu, Shenzhen

    Metal oxide materials are ubiquitous in nature and in our daily lives. For example, the Earth's mantle layer that makes up about 80% of our Earth's volume is composed of metal oxide materials, the cathode materials in the lithium-ion batteries that provide power for most of our mobile electronic devices are composed of metal oxides, the chemical components of the passivation layers on many kinds of metal materials that protect the metal from further corrosion are metal oxides. This thesis is composed of two major topics about the metal oxide materials in nature. The first topic is about our computational study of the iron chemistry in the Earth's lower mantle metal oxide materials, i.e. the bridgmanite (Fe-bearing MgSiO3 where iron is the substitution impurity element) and the ferropericlase (Fe-bearing MgO where iron is the substitution impurity element). The second topic is about our multiscale modeling works for understanding the nanoscale kinetic and thermodynamic properties of the metal oxide cathode interfaces in Li-ion batteries, including the intrinsic cathode interfaces (intergrowth of multiple types of cathode materials, compositional gradient cathode materials, etc.), the cathode/coating interface systems and the cathode/electrolyte interface systems. This thesis uses models based on density functional theory quantum mechanical calculations to explore the underlying physics behind several types of metal oxide materials existing in the interior of the Earth or used in the applications of lithium-ion batteries. The exploration of this physics can help us better understand the geochemical and seismic properties of our Earth and inspire us to engineer the next generation of electrochemical technologies.

  11. Peapod-like Li3 VO4 /N-Doped Carbon Nanowires with Pseudocapacitive Properties as Advanced Materials for High-Energy Lithium-Ion Capacitors.

    PubMed

    Shen, Laifa; Lv, Haifeng; Chen, Shuangqiang; Kopold, Peter; van Aken, Peter A; Wu, Xiaojun; Maier, Joachim; Yu, Yan

    2017-07-01

    Lithium ion capacitors are new energy storage devices combining the complementary features of both electric double-layer capacitors and lithium ion batteries. A key limitation to this technology is the kinetic imbalance between the Faradaic insertion electrode and capacitive electrode. Here, we demonstrate that the Li 3 VO 4 with low Li-ion insertion voltage and fast kinetics can be favorably used for lithium ion capacitors. N-doped carbon-encapsulated Li 3 VO 4 nanowires are synthesized through a morphology-inheritance route, displaying a low insertion voltage between 0.2 and 1.0 V, a high reversible capacity of ≈400 mAh g -1 at 0.1 A g -1 , excellent rate capability, and long-term cycling stability. Benefiting from the small nanoparticles, low energy diffusion barrier and highly localized charge-transfer, the Li 3 VO 4 /N-doped carbon nanowires exhibit a high-rate pseudocapacitive behavior. A lithium ion capacitor device based on these Li 3 VO 4 /N-doped carbon nanowires delivers a high energy density of 136.4 Wh kg -1 at a power density of 532 W kg -1 , revealing the potential for application in high-performance and long life energy storage devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Yttrium orthoaluminate nanoperovskite doped with Tm3+ ions as upconversion optical temperature sensor in the near-infrared region.

    PubMed

    Hernández-Rodriguez, M A; Lozano-Gorrín, A D; Lavín, V; Rodríguez-Mendoza, U R; Martín, I R

    2017-10-30

    The thermal sensing capability of the Tm 3+ -doped yttrium orthoaluminate nanoperovskite in the infrared range, synthetized by a sol-gel method, was studied. The temperature dependence of the infrared upconverted emission bands located at around 705 nm ( 3 F 2,3 → 3 H 6 ) and 800 nm ( 3 H 4 → 3 H 6 ) of YAP: Tm 3+ nanoperovskite under excitation at 1210 nm was analyzed from RT up to 425 K. Calibration of the optical sensor has been made using the fluorescence intensity ratio technique, showing a high sensitivity in the near-infrared compared to other trivalent rare-earth based optical sensors working in the same range. In addition, a second calibration procedure of the YAP: Tm 3+ optical sensor was performed by using the FIR technique on the emission band associated to the 3 H 4 → 3 H 6 transition in the physiological temperature range (293-333 K), showing a very high relative sensitivity compared with other rare-earth based optical temperature sensors working in the physiological range. Moreover, the main advantage compared with other optical sensors is that the excitation source and the upconverted emissions do not overlap, since they lie in different biological windows, thus allowing its potential use as an optical temperature probe in the near-infrared range for biological applications.

  13. Nitrogen-doped carbon nanofibers derived from polypyrrole coated bacterial cellulose as high-performance electrode materials for supercapacitors and Li-ion batteries

    DOE PAGES

    Lei, Wen; Han, Lili; Xuan, Cuijuan; ...

    2016-05-24

    Here, nitrogen-doped carbon nanofiber (NDCN) was synthesized via carbonization of polypyrrole (PPy) coated bacterial cellulose (BC) composites, where BC serves as templates as well as precursor, and PPy serves as the nitrogen source. The synthesized NDCN was employed as electrode for both supercapacitors and Li-ion batteries. The large surface area exposed to electrolyte resulting from the 3D carbon networks leads to sufficient electrode/electrolyte interface and creates shorter transport paths of electrolyte ions and Li + ion. Besides, the three types of N dopants in NDCN improve the electronic conductivity, as well as superior electrochemical performance.

  14. Spectroscopic study of Pr3+ ions doped Zinc Lead Tungsten Tellurite glasses for visible photonic device applications

    NASA Astrophysics Data System (ADS)

    Sharma, Ritu; Rao, A. S.; Deopa, Nisha; Venkateswarlu, M.; Jayasimhadri, M.; Haranath, D.; Prakash, G. Vijaya

    2018-04-01

    Zinc Lead Tungsten Tellurite (ZnPbWTe) glasses doped with different Pr3+ ion concentrations having the composition 5ZnO + 15PbO + 20WO3 + (60-x)TeO2 + xPr6O11 (where x = 0.5, 1, 1.5, 2.0 and 2.5 mol%) were prepared by using sudden quenching technique and characterized to understand their visible emission characteristic features using spectroscopic techniques such as absorption, excitation and emission. The Judd-Ofelt (J-O) theory has been applied to the absorption spectral features with an aim to evaluate various radiative properties for the prominent fluorescent levels of Pr3+ions in the as-prepared glasses. The emission spectra recorded for the as-prepared glasses under 468 nm excitation show three prominent emission transitions 3P0→3H6, 3P0→3F2 and 3P1→3F4, of which 3P0→3F2 observed in visible red region (648 nm), is relatively more intense. The intensity of 3P0→3F2 emission transition in the titled glasses increases up to 1mol% of Pr3+ ions and beyond concentration quenching is observed. Branching ratios (βR) and emission cross-sections (σse) were estimated for 3P0→3F2 transition to understand the luminescence efficiency in visible red region (648 nm). The CIE chromaticity coordinates were also evaluated in order to understand the suitability of these glasses for visible red luminescence devices. From the emission cross-sections, quantum efficiency and CIE coordinates, it was concluded that 1mol% of Pr3+ ions in ZnPbWTe glasses are quite suitable for preparing visible reddish orange luminescent devices.

  15. Hierarchically-structured hollow NiO nanospheres/nitrogen-doped graphene hybrid with superior capacity retention and enhanced rate capability for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Chen, Jiayuan; Wu, Xiaofeng; Liu, Ya; Gong, Yan; Wang, Pengfei; Li, Wenhui; Mo, Shengpeng; Tan, Qiangqiang; Chen, Yunfa

    2017-12-01

    A facile template-free synthesis strategy is demonstrated to fabricate nanostructured NiO/N-doped graphene hybrid, in which NiO hollow nanospheres with hierarchically mesoporous structure are tightly anchored on N-doped graphene matrix. The mesoporous shell of NiO can not only provide sufficient electrode/electrolyte contact areas to accelerate ion diffusion and electron exchange, but also efficiently mitigate the volume change that occurs during long-time reactions. Simultaneously, the reduced graphene oxide with doping nitrogen atoms are employed as effectively conductive backbone, further enhancing the electrochemical performances. When used as anodic material for lithium ion batteries, the synergistic system delivers a reversible capacity up to 1104.6 mAh g-1 after 150 cycles at a current density of 0.08 A g-1 and 422.3 mAh g-1 at a high charging rate of 4 A g-1, which is better than those of the bare counterparts and most other NiO-based materials reported in the previous literatures. The hierarchically hollow NiO nanostructure combined with N-doped graphene matrix provides a promising candidate applied in advanced anode materials for lithium ion batteries.

  16. Unusual doping effect of non-magnetic ion on magnetic properties of CuFe1-xGaxO2

    NASA Astrophysics Data System (ADS)

    Shi, Liran; Jin, Zhao; Chen, Borong; Xia, Nianming; Zuo, Huakun; Wang, Yeshuai; Ouyang, Zhongwen; Xia, Zhengcai

    2014-12-01

    The structural and magnetic properties of nonmagnetic Ga3+ ion doped CuFe1-xGaxO2 (x=0, 0.02, 0.03, and 0.05) single crystal samples have been investigated. In pulsed high magnetic fields, the field-induced multi-step transitions were observed in all the samples. Compared with pure CuFeO2, the transition temperatures, critical magnetic fields decrease and the magnetic hysteresis of the doped samples become small, which may result from the partial release of the spin frustration and the changes of the magnetic coupling both inter- and intra-planes due to the Ga3+ dopant. The magnetization measurements show an abnormal dilution behavior, especially in a lower temperature region, the magnetic moment was enhanced due to the nonmagnetic Ga3+ ion doping, the enhancement becomes more obviously in the sample with the Ga3+ doping level of x=0.03. These results may connected with the substitution of nonmagnetic Ga3+ ions destroying the stability of ground state and affecting the stability of the ferroelectricity incommensurate phase. Based on the experimental results, a super-cell model and their magnetic diagram were assumed.

  17. Growth and properties of oxygen- and ion-doped Bi2Sr2CaCu2O8+δ single crystals

    NASA Astrophysics Data System (ADS)

    Mitzi, D. B.; Lombardo, L. W.; Kapitulnik, A.; Laderman, S. S.; Jacowitz, R. D.

    1990-04-01

    A directional solidification method for growing large single crystals in the Bi2Sr2CaCu2O8+δ system is reported. Ion doping, with replacement of La for Sr and Y for Ca, as well as oxygen doping in these crystals has been explored. Doped and undoped crystals have been characterized using microprobe analysis, x-ray diffraction, thermogravimetric analysis, and magnetic and Hall measurements. Ion doping results in little change of the superconducting transition for substitution levels below 20-25%, while beyond this level the Meissner signal broadens and the low-temperature Meissner signal decreases. Microprobe analysis and x-ray diffraction performed on these more highly substituted single crystals provide evidence for inhomogeneity and phase segregation into regions of distinct composition. Annealing unsubstituted crystals in increasing partial pressures of oxygen reversibly depresses the superconducting transition temperature from 90 (as made) to 77 K (oxygen pressure annealed), while the carrier concentrations, as determined from Hall effect measurements, increase from n=3.1(3)×1021 cm-3 (0.34 holes per Cu site) to 4.6(3)×1021 cm-3 (0.50 holes per Cu site). No degradation of the Meissner transition or other indications of inhomogeneity or phase segregation with doping are noted, suggesting that oxygen-doped Bi2Sr2CaCu2O8+δ is a suitable system for pursuing doping studies. The decrease in Tc with concentration for 0.34<=n<=0.50 indicates that a high-carrier-concentration regime exists in which Tc decreases with n and suggests that this decrease does not arise from material inhomogeneity or other materials problems. An examination of the variation of Tc with the density of states and lattice constants for all of the doped and undoped superconducting samples considered here indicates that changes in Tc with doping are primarily affected by changes in the density of states (or carrier concentration) rather than by structural variation induced by the doping.

  18. Heavy doping of CdTe single crystals by Cr ion implantation

    NASA Astrophysics Data System (ADS)

    Popovych, Volodymyr D.; Böttger, Roman; Heller, Rene; Zhou, Shengqiang; Bester, Mariusz; Cieniek, Bogumil; Mroczka, Robert; Lopucki, Rafal; Sagan, Piotr; Kuzma, Marian

    2018-03-01

    Implantation of bulk CdTe single crystals with high fluences of 500 keV Cr+ ions was performed to achieve Cr concentration above the equilibrium solubility limit of this element in CdTe lattice. The structure and composition of the implanted samples were studied using secondary ion mass spectrometry (SIMS), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD) and Rutherford backscattering spectrometry (RBS) to characterize the incorporation of chromium into the host lattice and to investigate irradiation-induced damage build-up. It was found that out-diffusion of Cr atoms and sputtering of the targets alter the depth distribution and limit concentration of the projectile ions in the as-implanted samples. Appearance of crystallographically oriented, metallic α-Cr nanoparticles inside CdTe matrix was found after implantation, as well as a strong disorder at the depth far beyond the projected range of the implanted ions.

  19. Role of associated defects in oxygen ion conduction and surface exchange reaction for epitaxial samaria-doped ceria thin films as catalytic coatings

    DOE PAGES

    Yang, Nan; Shi, Yanuo; Schweiger, Sebastian; ...

    2016-05-18

    Samaria-doped ceria (SDC) thin films are particularly important for energy and electronic applications such as micro-solid oxide fuel cells, electrolysers, sensors and memristors. In this paper we report a comparative study investigating ionic conductivity and surface reactions for well-grown epitaxial SDC films varying the samaria doping concentration. With increasing doping above 20 mol% of samaria, an enhancement in the defect association was observed by Raman spectroscopy. The role of such defect associates on the films` oxygen ion transport and exchange was investigated by electrochemical impedance spectroscopy and electrochemical strain microscopy (ESM). The measurements reveal that the ionic transport has amore » sharp maximum in ionic conductivity and drop in its activation energy down to 0.6 eV for 20 mol% doping. Increasing the doping concentration further up to 40 mol%, raises the activation energy substantially by a factor of two. We ascribe the sluggish transport kinetics to the "bulk" ionic-near ordering in case of the heavily doped epitaxial films. Analysis of the ESM first order reversal curve measurements indicate that these associated defects may have a beneficial role by lowering the activation of the oxygen exchange "surface" reaction for heavily doped 40 mol% of samaria. We reveal in a model experiment through a solid solution series of samaria doped ceria epitaxial films that the occurrence of associate defects in the bulk affects the surface charging state of the films to increase the exchange rates. Lastly, the implication of these findings are the design of coatings with tuned oxygen surface exchange by control of bulk associate clusters for future electro-catalytic applications.« less

  20. EPR and optical studies of Cu2+ ions doped in magnesium potassium phosphate hexahydrate single crystals

    NASA Astrophysics Data System (ADS)

    Kripal, Ram; Shukla, Santwana

    2011-03-01

    An electron paramagnetic resonance (EPR) study of Cu2+-doped magnesium potassium phosphate is performed at liquid nitrogen temperature (LNT; 77 K). Two magnetically non-equivalent sites for Cu2+ are observed. The spin Hamiltonian parameters are determined with the fitting of spectra to a rhombic symmetry crystalline field. The ground state wavefunction is also determined. The g-anisotropy is evaluated and compared with the experimental value. With the help of an optical study, the nature of the bonding in the complex is discussed.

  1. Simulation of the low earth orbital atomic oxygen interaction with materials by means of an oxygen ion beam

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.; Paulsen, Phillip E.; Steuber, Thomas J.

    1989-01-01

    Atomic oxygen is the predominant species in low-Earth orbit between the altitudes of 180 and 650 km. These highly reactive atoms are a result of photodissociation of diatomic oxygen molecules from solar photons having a wavelength less than or equal to 2430A. Spacecraft in low-Earth orbit collide with atomic oxygen in the 3P ground state at impact energies of approximately 4.2 to 4.5 eV. As a consequence, organic materials previously used for high altitude geosynchronous spacecraft are severely oxidized in the low-Earth orbital environment. The evaluation of materials durability to atomic oxygen requires ground simulation of this environment to cost effectively screen materials for durability. Directed broad beam oxygen sources are necessary to evaluate potential spacecraft materials performance before and after exposure to the simulated low-Earth orbital environment. This paper presents a description of a low energy, broad oxygen ion beam source used to simulate the low-Earth orbital atomic oxygen environment. The results of materials interaction with this beam and comparison with actual in-space tests of the same meterials will be discussed. Resulting surface morphologies appear to closely replicate those observed in space tests.

  2. Judd-Ofelt analysis and spectral properties of Dy3+ ions doped niobium containing tellurium calcium zinc borate glasses

    NASA Astrophysics Data System (ADS)

    Ravi, O.; Reddy, C. Madhukar; Reddy, B. Sudhakar; Deva Prasad Raju, B.

    2014-02-01

    Niobium containing tellurium calcium zinc borate (TCZNB) glasses doped with different concentrations of Dy3+ ions were prepared by the melt quenching method and their optical properties have been studied. The Judd-Ofelt (J-O) intensity parameters Ωt (t=2, 4 and 6) were calculated using the least square fit method. Based on the magnitude of Ω2 parameter the hypersensitivity of 6H15/2→6F11/2 has also been discussed. From the evaluated J-O intensity parameters as well as from the emission and lifetime measurements, radiative transition properties such as radiative transition probability rates and branching ratios were calculated for 4F9/2 excited level. It is found that for Dy3+ ion, the transition 4F9/2→6H13/2 shows highest emission cross-section at 1.0 mol% TCZNB glass matrix. From the visible luminescence spectra, yellow to blue (Y/B) intensity ratios and chromaticity color coordinates were also estimated. The TCZNB glasses exhibit good luminescence properties and are suitable for generation of white light.

  3. Incorporation of surface plasmon resonance with novel valinomycin doped chitosan-graphene oxide thin film for sensing potassium ion.

    PubMed

    Zainudin, Afiq Azri; Fen, Yap Wing; Yusof, Nor Azah; Al-Rekabi, Sura Hmoud; Mahdi, Mohd Adzir; Omar, Nur Alia Sheh

    2018-02-15

    In this study, the combination of novel valinomycin doped chitosan-graphene oxide (C-GO-V) thin film and surface plasmon resonance (SPR) system for potassium ion (K + ) detection has been developed. The novel C-GO-V thin film was deposited on the gold surface using spin coating technique. The system was used to monitor SPR signal for K + in solution with and without C-GO-V thin film. The K + can be detected by measuring the SPR signal when C-GO-V thin film is exposed to K + in solution. The sensor produces a linear response for K + ion up to 100ppm with sensitivity and detection limit of 0.00948°ppm -1 and 0.001ppm, respectively. These results indicate that the C-GO-V film is high potential as a sensor element for K + that has been proved by the SPR measurement. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Highly nitrogen-doped carbon capsules: scalable preparation and high-performance applications in fuel cells and lithium ion batteries.

    PubMed

    Hu, Chuangang; Xiao, Ying; Zhao, Yang; Chen, Nan; Zhang, Zhipan; Cao, Minhua; Qu, Liangti

    2013-04-07

    Highly nitrogen-doped carbon capsules (hN-CCs) have been successfully prepared by using inexpensive melamine and glyoxal as precursors via solvothermal reaction and carbonization. With a great promise for large scale production, the hN-CCs, having large surface area and high-level nitrogen content (N/C atomic ration of ca. 13%), possess superior crossover resistance, selective activity and catalytic stability towards oxygen reduction reaction for fuel cells in alkaline medium. As a new anode material in lithium-ion battery, hN-CCs also exhibit excellent cycle performance and high rate capacity with a reversible capacity of as high as 1046 mA h g(-1) at a current density of 50 mA g(-1) after 50 cycles. These features make the hN-CCs developed in this study promising as suitable substitutes for the expensive noble metal catalysts in the next generation alkaline fuel cells, and as advanced electrode materials in lithium-ion batteries.

  5. Up-conversion green emission of Yb3+/Er3+ ions doped YVO4 nanocrystals obtained via modified Pechini's method

    NASA Astrophysics Data System (ADS)

    Szczeszak, Agata; Runowski, Marcin; Wiglusz, Rafal J.; Grzyb, Tomasz; Lis, Stefan

    2017-12-01

    A series of lanthanide doped yttrium vanadates were prepared by Pechini's method (sol-gel process). The as-prepared precursors, in the presence of citric acid, were calcined in the temperature range of 600-900 °C. The obtained products were composed of small nanoparticles, in the size range of 20-50 nm, depending on the annealing temperature, exhibiting a bright green up-conversion emission, under NIR laser irradiation, and emission lifetimes in the range of 4.7-18.3 μs. Their structural, morphological and spectroscopic properties were investigated in detail by XRD, HR-TEM including FFT analysis, EDX and spectroscopic techniques (emission, power dependence and emission kinetics). The luminescence quenching phenomenon, manifested in a decrease of up-conversion intensity and shortening of emission lifetime, was observed with increasing of the Yb3+ ion concentration and decreasing the particle size. The optimal concentration of the Yb3+ ions was found to be 15 mol% (YVO4: Yb3+ 15 mol%, Er3+ 2 mol%).

  6. Er 3+-Yb 3+ co-doped glass waveguide amplifiers using ion exchange and field-assisted annealing

    NASA Astrophysics Data System (ADS)

    Zhang, X. Z.; Liu, K.; Mu, S. K.; Tan, C. Z.; Zhang, D.; Pun, E. Y. B.; Zhang, D. M.

    2006-12-01

    Er 3+-Yb 3+ co-doped waveguide amplifiers fabricated using thermal two-step ion-exchange are demonstrated. K +-Na + ion-exchange process was first carried out in pure KNO 3 molten bath, and then field-assisted annealing (FAA) was used to make the buried waveguides. The effective buried depth is estimated to be ˜3.4 μm for the buried FAA waveguides. With the use of cut-back method, the fiber-to-guide coupling loss of ˜4.38 dB, the waveguide loss of ˜2.27 dB/cm, and Er 3+ absorption loss ˜5.7 dB were measured for a ˜1.24-cm-long waveguide. Peak relative gain of ˜7.0 dB is obtained for a ˜1.24-cm-long waveguide. The potential for the fabrication of compact optical amplifiers operating in the range of 1520-1580 nm is also demonstrated.

  7. Potentiometric determination of pantoprazole using an ion-selective sensor based on polypyrrole doped films.

    PubMed

    Noronha, Bárbara V; Bindewald, Eduardo H; de Oliveira, Michelle C; Papi, Maurício A P; Bergamini, Márcio F; Marcolino, Luiz H

    2014-10-01

    The present work reports for the first time the use of polypyrrole (PPy) doped film for development of a potentiometric disposable sensor for determination of pantoprazole (PTZ), a drug used for ulcer treatment. Selective potentiometric response has been found by using a membrane of PPy doped with PTZ anions prepared under galvanostatic conditions at graphite pencil electrode (GPEM/PPy-PTZ) surface. Potentiometric response has been influenced for conditions adopted in polymerization and measurement step. After optimization of experimental (e.g. pH and time of conditioning) and instrumental parameters (e.g. current density and electrical charge) a linear analytical curve from 1.0 × 10(-5) to 1.1 × 10(-2) mol L(-1) with a slope of calibration of the 57.6 mV dec(-1) and limit of detection (LOD) of 6.9 × 10(-6) mol L(-1) was obtained. The determination of the PTZ content in pharmaceutical samples using the proposed methodology and official method recommended by Brazilian Pharmacopeia are in agreement at the 95% confidence level and within an acceptable range of error. Copyright © 2014 Elsevier B.V. All rights reserved.

  8. Generation of (F+2)_AH Centres in Sodium Ion Doped KCl:CO^{2-3}

    NASA Astrophysics Data System (ADS)

    Diaf, M.; Chihi, I.; Hamaïdia, A.; Akrmi, El.

    1996-01-01

    We demonstrate that (F+2)AH centres of KCl may be obtained from crystals doped with K{2}CO{3} and NaCl, grown by the Czochralski method in open atmosphere. The optical properties of (F+2)AH centres thus produced are exactly the same as those of (F+2)AH centres prepared by the usual technique, which involves superoxide doping and a controlled atmosphere. Nous montrons que les centres (F+2)AH de KCl peuvent être obtenus à partir de cristaux dopés par K{2}CO{3} et NaCl, fabriqués par la méthode de Czochralski à l'air libre. Les propriétés optiques des centres (F+2)AH ainsi produits sont exactement les mêmes que celles des centres (F+2)AH préparés par la technique habituelle, qui comporte le dopage par un superoxyde et l'emploi d'une atmosphère contrôlée.

  9. Modeling the near-Earth interaction between ring current ions and exospheric neutrals: escape through energetic neutral atoms (ENAs)

    NASA Astrophysics Data System (ADS)

    LLera, K.; Goldstein, J.; McComas, D. J.; Valek, P. W.

    2016-12-01

    The two major loss processes for ring current decay are precipitation and energetic neutral atoms (ENAs). Since the exospheric neutral density increases with decreasing altitudes, precipitating ring current ions (reaching down to 200 - 800 km in altitude) also produce low-altitude ENA signatures that can be stronger than the ring current emission at equatorial distances ( 2 - 9 Re). The higher density results in multiple collisions between the ring current ions and exospheric oxygen. The affect on hydrogen ions is the focus of this study. Since the H particle sustains energy loss ( 36 eV) at each neutralizing or re-ionizing interaction, the escaped ENAs do not directly reflect the ring current properties. We model the energy loss due to multiple charge exchange and electron stripping interactions of 1 - 100 keV precipitating ring current ions undergo before emerging as low-altitude ENAs. The H particle is either an ion or an ENA throughout the simulation. Their lifetime is analytically determined by the length of one mean free path. We track the ion state with Lorentz motion while the ENA travels ballistically across the geomagnetic field. Our simulations show the energy loss is greater than 20% for hydrogen ring current ions below 30 keV (60 keV for the simulations that wander equatorward). This is the first quantification of the energy loss associated with the creation of low-altitude ENAs. Our model (currently constrained in the meridional plane) has revealed characteristics on how precipitation is affected by the near-Earth neutral exosphere. This ion-neutral interaction removes particles from the loss cone but promotes loss through ENA generation. These findings should be implemented in models predicting the ring current decay and used as an analysis tool to reconstruct the ring current population from observed low-altitude ENAs.

  10. Enhancing visible light photocatalytic and photocharge separation of (BiO){sub 2}CO{sub 3} plate via dramatic I{sup −} ions doping effect

    SciT

    Liang, Lei; Cao, Jing; Anhui Collaborative Innovation Center of Advanced Functional Composite, Huaibei, 235000, Anhui

    Highlights: • Novel I-(BiO){sub 2}CO{sub 3} was prepared by a facile chemical precipitation method. • I{sup −} ions impurity level located on the top of valence band of (BiO){sub 2}CO{sub 3}. • I{sup −} ions doping largely improved photocatalytic activity of I-(BiO){sub 2}CO{sub 3}. • I-(BiO){sub 2}CO{sub 3} displayed excellent photocharge separation efficiency. - Abstract: Novel I{sup −} ions doped (BiO){sub 2}CO{sub 3} (I-(BiO){sub 2}CO{sub 3}) photocatalysts were successfully synthesized via a facile chemical precipitation method. Under visible light (λ > 400 nm), I-(BiO){sub 2}CO{sub 3} displayed much higher activity for rhodamine B and dichlorophenol degradation than the undoped (BiO){submore » 2}CO{sub 3}. The pseudo-first-order rate constant k{sub app} of RhB degradation over 15.0% I-(BiO){sub 2}CO{sub 3} was 0.54 h{sup −1}, which is 11.3 times higher than that of (BiO){sub 2}CO{sub 3}. The doped I{sup −} ions formed an impurity level on the top of valence band of (BiO){sub 2}CO{sub 3} and induced much more visible light to be absorbed. The enhanced photocurrent and surface photovoltage properties were detected, which strongly ensures the efficient separation of electrons and holes in I-(BiO){sub 2}CO{sub 3} system under visible light. It provides a facile way to improve the photocatalytic activity of the wide-band-gap (BiO){sub 2}CO{sub 3} via intense doping effect of I{sup −} ions.« less

  11. High capacity and stability of Nb-doped Li3VO4 as an anode material for lithium ion batteries

    NASA Astrophysics Data System (ADS)

    Zhao, Long; Duan, He; Zhao, Yanming; Kuang, Quan; Fan, Qinghua; Chen, Lei; Dong, Youzhong

    2018-02-01

    To improve the electrochemical performance of Li3VO4, a series of Li3NbxV1-xO4 compounds are prepared via sol-gel method. The similar ionic radii of Nb5+ and V5+ in octahedral coordination make it possible to form single-phased Li3NbxV1-xO4 (0 ≤ x ≤ 0.15). Theoretical calculations show that Li-ions migrate along the c-axis diffusion channel in a curved hopping route. The larger lattice constant caused by the substitution of V with Nb enhances the cross-sectional area, which indirectly provides a higher diffusion coefficient for Li-ion migration. Benefitting from high electronic conductivity (around two orders of magnitude) and good lithium-ion diffusion coefficient, the Li3NbxV1-xO4 (x = 0.02) exhibits the best electrochemical property as an anode of LIBs in comparison to other Li3NbxV1-xO4(x = 0, 0.01, 0.03, 0.04). At the current density of 30 mA g-1, the charge capacity of pure Li3VO4 is around 440 mA h g-1, whereas the Li3NbxV1-xO4 (x = 0.02) shows a higher capacity of 550 mA h g-1. Additionally, the charge/discharge capacities for Nb-doped samples are almost twice to those of the undoped Li3VO4 when the current density increases to1500 mA g-1.

  12. Fabrication of single Ga-doped ZnS nanowires as high-gain photosensors by focused ion beam deposition

    NASA Astrophysics Data System (ADS)

    Yen, Shih-Hsiang; Hung, Yu-Chen; Yeh, Ping-Hung; Su, Ya-Wen; Wang, Chiu-Yen

    2017-09-01

    ZnS nanowires were synthesized via a vapor-liquid-solid mechanism and then fabricated into a single-nanowire field-effect transistor by focused ion beam (FIB) deposition. The field-effect electrical properties of the FIB-fabricated ZnS nanowire device, namely conductivity, mobility and hole concentration, were 9.13 Ω-1 cm-1, 13.14 cm2 V-1 s-1and 4.27 × 1018 cm-3, respectively. The photoresponse properties of the ZnS nanowires were studied and the current responsivity, current gain, response time and recovery time were 4.97 × 106 A W-1, 2.43 × 107, 9 s and 24 s, respectively. Temperature-dependent I-V measurements were used to analyze the interfacial barrier height between ZnS and the FIB-deposited Pt electrode. The results show that the interfacial barrier height is as low as 40 meV. The energy-dispersive spectrometer elemental line scan shows the influence of Ga ions on the ZnS nanowire surface on the FIB-deposited Pt contact electrodes. The results of temperature-dependent I-V measurements and the elemental line scan indicate that Ga ions were doped into the ZnS nanowire, reducing the barrier height between the FIB-deposited Pt electrodes and the single ZnS nanowire. The small barrier height results in the FIB-fabricated ZnS nanowire device acting as a high-gain photosensor.

  13. P-type doping of GaN(000\\bar{1}) by magnesium ion implantation

    NASA Astrophysics Data System (ADS)

    Narita, Tetsuo; Kachi, Tetsu; Kataoka, Keita; Uesugi, Tsutomu

    2017-01-01

    Magnesium ion implantation has been performed on a GaN(000\\bar{1}) substrate, whose surface has a high thermal stability, thus allowing postimplantation annealing without the use of a protective layer. The current-voltage characteristics of p-n diodes fabricated on GaN(000\\bar{1}) showed distinct rectification at a turn-on voltage of about 3 V, although the leakage current varied widely among the diodes. Coimplantation with magnesium and hydrogen ions effectively suppressed the leakage currents and device-to-device variations. In addition, an electroluminescence band was observed at wavelengths shorter than 450 nm for these diodes. These results provide strong evidence that implanted magnesium ions create acceptors in GaN(000\\bar{1}).

  14. Characterization of flux-grown Trace-element-doped titanite using the high-mass-resolution ion microprobe (SHRIMP-RG)

    Mazdab, F.K.

    2009-01-01

    Crystals of titanite can be readily grown under ambient pressure from a mixture of CaO, TiO2 and SiO2 in the presence of molten sodium tetraborate. The crystals produced are euhedral and prismatic, lustrous and transparent, and up to 5 mm in length. Titanite obtained by this method contains approximately 4300 ppm Na and 220 ppm B contributed from the flux. In addition to dopant-free material, titanite containing trace alkali and alkaline earth metals (K, Sr, Ba), transition metals (Sc, Cr, Ni, Y, Zr, Nb, Hf and Ta), rare-earth elements (REE), actinides (Th, U) and p-block elements (F, S, Cl, Ge, Sn and Pb) have been prepared using the same procedure. Back-scattered electron (BSE) imaging accompanied by ion-microprobe (SHRIMP-RG) analysis confirms significant incorporation of selected trace-elements at structural sites. Regardless of some zonation, the large size of the crystals and broad regions of chemical homogeneity make these crystals useful as experimental starting material, and as matrix-matched trace-element standards for a variety of microbeam analytical techniques where amorphous titanite glass, heterogeneous natural titanite or a non-titanite standard may be less than satisfactory. Trace-element-doped synthetic crystals can also provide a convenient proxy for a better understanding of trace-element incorporation in natural titanite. Comparisons with igneous, authigenic and high-temperature metasomatic titanite are examined. The use of high-mass-resolution SIMS also demonstrates the analytical challenges inherent to any in situ mass-spectrometry-based analysis of titanite, owing to the production of difficult-to-resolve molecular interferences. These interferences are dominated by Ca-Ca, Ca-Ti and Ti-Ti dimers that are significant in the mass range of 80-100, affecting all isotopes of Sr and Zr, as well as 89Y and 93Nb. Methods do exist for the evaluation of interferences by these dimers and of polyatomic interferences on the LREE.

  15. Effect of upstream ULF waves on the energetic ion diffusion at the earth's foreshock: Theory, Simulation, and Observations

    NASA Astrophysics Data System (ADS)

    Otsuka, F.; Matsukiyo, S.; Kis, A.; Hada, T.

    2017-12-01

    Spatial diffusion of energetic particles is an important problem not only from a fundamental physics point of view but also for its application to particle acceleration processes at astrophysical shocks. Quasi-linear theory can provide the spatial diffusion coefficient as a function of the wave turbulence spectrum. By assuming a simple power-law spectrum for the turbulence, the theory has been successfully applied to diffusion and acceleration of cosmic rays in the interplanetary and interstellar medium. Near the earth's foreshock, however, the wave spectrum often has an intense peak, presumably corresponding to the upstream ULF waves generated by the field-aligned beam (FAB). In this presentation, we numerically and theoretically discuss how the intense ULF peak in the wave spectrum modifies the spatial parallel diffusion of energetic ions. The turbulence is given as a superposition of non-propagating transverse MHD waves in the solar wind rest frame, and its spectrum is composed of a piecewise power-law spectrum with different power-law indices. The diffusion coefficients are then estimated by using the quasi-linear theory and test particle simulations. We find that the presence of the ULF peak produces a concave shape of the diffusion coefficient when it is plotted versus the ion energy. The results above are used to discuss the Cluster observations of the diffuse ions at the Earth's foreshock. Using the density gradients of the energetic ions detected by the Cluster spacecraft, we determine the e-folding distances, equivalently, the spatial diffusion coefficients, of ions with their energies from 10 to 32 keV. The observed e-folding distances are significantly smaller than those estimated in the past statistical studies. This suggests that the particle acceleration at the foreshock can be more efficient than considered before. Our test particle simulation explains well the small estimate of the e-folding distances, by using the observed wave turbulence spectrum

  16. Electrochemical capacitor materials based on carbon and luminophors doped with lanthanide ions

    NASA Astrophysics Data System (ADS)

    Kubasiewicz, Konrad; Slesinski, Adam; Gastol, Dominika; Lis, Stefan; Frackowiak, Elzbieta

    2017-10-01

    The described research is focused on the hybrid, bi-functional composite materials dedicated to the electrochemical capacitor electrodes. The novel material exhibits both luminescent and capacitive properties. The fabrication process of semi-products and the final composite is described. The structure and homogeneity of luminophors are confirmed with the XRD analysis. The morphology of materials is also determined by TEM and SEM images. The detailed spectroscopic characterization includes excitation and emission spectra, luminescence decay curves, emission lifetimes, CIE chromaticity indexes. The electrochemical studies of composite electrodes carried out by cyclic voltammetry and impedance spectroscopy exhibit good charge propagation. For the first time, inorganic luminophors containing doped LaF3 and GdVO4 have been successfully used for electrochemical capacitor. It is the primary stage to design a new generation of light emitting capacitors utilizing more stable inorganic luminophors than organic-based ones.

  17. Synthesis and Characterization of YVO4-Based Phosphor Doped with Eu3+ Ions for Display Devices

    NASA Astrophysics Data System (ADS)

    Thakur, Shashi; Gathania, Arvind K.

    2015-10-01

    YVO4:Eu nanophosphor has been synthesized by the sol-gel method. Samples were characterized by x-ray diffraction (XRD), energy-dispersive x-ray spectroscopy, Fourier-transform infrared spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, photoluminescence, and Raman spectroscopy. The XRD profile confirms the tetragonal phase of the Eu3+-doped YVO4 nanophosphor. The efficiency of the prepared phosphor was analyzed by means of its emission spectral profile. We also observed rich red emission from the prepared phosphor on excitation by an ultraviolet source. The calculated Commission International de l'Éclairage coordinates reveal excellent color purity efficiency. Such luminescent powder is useful as red phosphor in display device applications.

  18. Optical and physical properties of sodium lead barium borate glasses doped with praseodymium ion